Gaming performance issues?

Question

First of all, I'd like to ask that you bear with my nubness while I fumble my question out.  Hmm... ok.
In anticipation of HL2, I purchased all the parts I needed for a system and built one (my first and only time so far) in September 2003.  Having recently come into some money, I kind of went pretty far out.  Here are the main system specs, which have remained unchanged since September:
Intel P4 3.00 Ghz
MSI MS-6758 ( the 875P Neo)
Corsair TWINX1024-3200LLPT (2x512)
Turbolink 420 Watt PSU
PNY Geforce FX 5900 Ultra
Creative Soundblaster Audigy Gamer
Western Digital 160 GB HD
Sony CD-RW/DVD-R drive
Sony DVD drive
(XP Home Edition SP1)
Sounds pretty nice, doesn't it?  So when I get a 3dMark03 score of 4772 -- less than half of what most people with nearly identical systems got -- and an average framerate of 14 frames per second in Half Life at 1024x768 with no AA or other special junk running, well, I don't know what to think.
The first thing I did was check on all of my drivers.  I'm currently running the most recent official drivers for all of my hardware, and framerates are as low as before.  So, then I decided to bite the bullet and flash my bios (which was thankfully a lot easier than I had built it up to be), since it was nearly a year out of date.  The new and improved bios yielded no performance gains, but then I'm not quite sure if it should have or not.  As a nub, the general rule of thumb I follow is "the newer, the better."  I realize that it's not always so in some cases, but it's worked well enough for me so far....
So... I'm perplexed.  And because I don't know if it's an issue with a single component or anything, it's hard to find answers online.  So I bring it up to you to help a nub.  Please, if you have any idea what I'm talking about and what I could do to fix it, I would build a 50 foot stone statue of you and name my firstborn whatever you desire.
If you need any clarification, I'll be refreshing this thread all night.  Thanks... I hope.

Answer 1

Well, thanks for all of the replies.  I'm using the patched version of 3dMark03 and the 56.72 Forceware drivers.  I should have phrased my question differently.  It's still basically the same thing, but the focus isn't the benchmark test -- it's the abysmal framerates in games.  I can certainly understand a lower fps in games like Far Cry, but with stuff like Half Life... the computer I used two years ago was doing better than this one.  (Has anyone else experienced similar issues?)
And actually, as a matter of fact, this one used to do quite well.  I had a giant general f*ck-up, though, and was forced to reformat and basically restart everything from where I began, and I guess this is where the problem came in.  
As for OCing, I want to do some more research on that before I potentially kill my system trying to reach the 6000 mark ;o.  As it stands, I need to clean a lot of dust out of my PC (my idle temp is 44 C :X) or maybe get a cooler room to put it in.  That said, overall system performance has been a good deal better since I installed newer drivers, new bios, etc... it's just not affecting games as much.
And Sandra has been a big help in more ways than I can recount, Aaron, thanks.
Question:  What about my video card BIOS?  Is that something I should look into updating, or what?
Thanks once more.