E mac freezing up frequently OS X upgrades

Question

I have the e mac 1.25 ghz power pc g4 processor. 
I installed a 1 gb ram module, and left the original 256 mb module installed.  The thing about this is the 1 gb module is the same RAM I used in my windows pc.  Got a good price on it from Fry's.  It is PC 2700 133 mhz.  Could this be the cause of the freeze ups ?  What is the maximum amount of ram i can use in this computer?  When i look at the 'about this mac' memory speed for the 1gb module says PC2700U-25330, the 256mb module says PC2700U-30330.  Is that a problem?
Also, I have been running into several roadblocks because I am running OS X 10.3.9.  A lot of programs require newer software.  What is the newest OSX version that will work in my computer?
<Serial Number Edited by Host>

Answer 1

There are a large number of 1.25 emacs with near-fatal logic board issues. They usually fall in these serial number ranges:
G8412xxxxxx- G8520xxxxxx
YM412xxxxxx - YM520xxxxxx
VM440xxxxxx - VM516xxxxxx
As you see, you eMac falls smack in the middle of the first range, so there is a good chance that's the source of the problem. There was a repair extension program from this issues but it expired in June 2009. In today's market, there is no practical fix that does not involve other used (and potentially defective) parts and cost 2-3X the current value of the computer.
That said, the new RAM stick could be at play if you never had trouble before. Take it out and see if thing straighten up. I like Fry's but they are pretty Windows-centric in the RAM dept at the store I usually visit. I bough this RAM from OWC:
1GB PC2700 DDR 333MHz CAS 2.5 184 Pin DIMM
for my wife's 1.42 eMac and it's worked great--tested in a mAc by the vendor. However, I'm on the road at the moment so can't check the extended numbers of that module until Monday evening.
If you get stability, and get the extra RAM working, you can install up to OS 10.5. It's still available but you have to call the US Apple store--it's not on their web sites.
It may not be available outside North America, and you don't say where you are.