[Athlon64] Noob needs help optimizing new system

Question

Sorry to post yet another thread, but I've been lurking for the past few days and I only get bits and pieces of what I need. I'm pretty clueless about this stuff as it's my first home-built system
See my sig for system info...
I'm needing help with bios settings. The pertinent stuff (I think - hopefully I got it all down):
CELL MENU
CPU Clock speed: 2200
DDR Memory Freq: 100.0 MHz
High performance mode: Manual
Cool n quiet: Disable
HT Freq: 800 MHz
Dynamic overclocking: Disable
Adjust CPU Ratio: Auto
AGP Freq: By Default
HT Voltage: Auto
Mem voltage: Auto
CPU voltage: Auto
AGP Voltage: Auto
Spread sectrum: Disable
DRAM
DRAM Clock Mode: Manual
Mem clock value: DDR200
CAS Latency: SPD
Burst Length: 8 Beat
Bank Interleaving: Auto
Active to CMD (Trcd): SPD
Active to precharge (Tras): SPD
Precharge to active (Tvp): SPD
DRAM IT Timing: Disable
ADVANCED CHIPSET FEATURES
AGP Mode: Auto (this is "greyed out")
AGP Fast write: Enabled
AGP Aperture size: 128
VLink 8X supported: Enabled
My questions mainly concern memory. I bought all this stuff at the Tiger Direct outlet store in Naperville, Illinois. I had intended to buy the K8T Neo-FSR (754 pin), but they were supposedly out of the 754 pin 3400+, and this board/CPU combo had a $100 rebate. Yeah, it's one of those deals with the odd 939 pin 3400+ that everyone has been talking about.
In any case, I already had the Corsair CMX512-3200C2PT picked out, as Corsair said it was compatible with the board. I wasn't aware of the MSI compitibility chart until I came here later that night. I STILL can't find that chart off of the MSI web site.
Anyway, I got it all hooked up and got the standard 4 red LEDs. Not knowing what to do, I took it back to Tiger Direct and the tech played around with it until he stuck an el-cheapo stick (Corsair VS512MB400) in there and it worked. But it only works in slot 2. So here I am.
I started to run memtest86, but it took too long to run and I aborted it for now. For what it's worth, it said the RAM CAS value is 2.5-2-2-5. I don't know what the hell that means, but I know it's important.
My questions:
1. I assume I need manually to set my memory clock value to DDR400?
2. Now that I can get the thing to post, is there any chance I could get the "good" Corsair memory to work by setting the correct latency/CAS values? Again, I don't know what I'm talking about, so forgive my ignorance. What I'm wondering is if I can set everything to what Corsair recommends while I have the cheap memory in there and then replace it with the good stuff?
3. With this board, am I better off with double-sided or single-sided sticks? As I said, I went into the store intending to buy the Neo 754-pin board, but they were out of the Athlon 3400+ in 754 and only had the 939 pin.
4. Anything else in my bios settings that stand out and need to be addressed? I want to make sure everything is optimized.
EDIT: I almost forgot: My CPU temp is runing around 42-49 degrees. Am I in the danger zone? I just bought a generic cooler for now and intend to get a Thermalright XP-120, but I can't find it locally, so it will have to wait.
AND FINALLY...
I don't know if this is related to anything above, but I have been having a hell of a time getting the 6600GT to run DirectX9+ games. The latest drivers for Windows 98SE was 66.94. Yes, XP will be installed soon, but for now... It was failing on dxdiag test for Direct3d 9 and also the third DirectDraw test. I was about to give up and take it back when I discovered that a new beta driver came out today (71.84). I installed it and it passed all of the dxdiag tests. I thought I was in hawg-heaven, but when I run Call of Duty (the only DX9 game I have besides HL2), it slows to an absolute clawl. The level starts out somewhat normal at first, but quickly slows down to the point that performance can only be measured in seconds per frame! All of the patches 1.5 and 1.51 for UO have been installed, but that shouldn't make a bit of difference.
If I don't get my CoD fix soon I'm gonna reinstall that Geforce3.
Thanks much and sorry again for such a long post.

Answer 1

Thanks everyone for the recent replies, but I started this thread almost a month ago (March 3rd), and much has changed since then.
New PSU (see sig).
Replaced the PNY Geforce6600GT with a eVGA 6800
Added another stick of the Corsair Value Select 512 RAM. I didn't even bother trying to get the "primo" CMX stick to work. I just returned it.
Went from Windows 98SE to XP Home.
The PSU did nothing for me at all, but I suppose it's better to have some headroom in the amperage.
The biggest performance booster was the additional 512MB of RAM. It wouldn't have done me any good in 98SE, but I was shocked at how much it helps XP. Quitting a game is almost instant now, where before it would take a good two minutes or so for XP to recover itself.
As for games running slow, the 6800 fixed it right up. CoD absolutely screams now, as does everything else I've thrown at it (HL2, Doom 3, Far Cry). I think the 6600GT was just bad or there is a serious driver problem with the 6600GT's. Went from 3DMark03 score of around 5000 (when it didn't crash) to above 9000 now. And this was all before adding the additional RAM.
Oh yeah, I bought a 74GB Raptor. No RAID for now though. So far I'm not real impressed with the performance. I'm running off of the VIA controller, since my board doesn't have the Promise controller. I don't see much improvement in loading times as compared to the 40GB 7200rpm Maxtor I have running on IDE1. The only time it beats the pants off the Maxtor is defragging. But there's only so much entertainment value in that.  The Sandra "file system benchmark" gave me 57 MB/s, which seems pathetic, but I've read some posts here where others are getting an identical rate.
And I'm not too happy to discover, too late, that my overclocking capabilities are severely limited while using SATA.
I do have one more question for now:
When I installed the second 512MB stick, I originally had both sticks in slot 1 and 2. I ran Sandra's memory bandwidth benchmark and got a much lower score than with the single stick (around 3500 MB/s). WHen I had the sticks in 1 and 3, it jumped up to close to 6000 MB/s. Why is that? Just curious.