So, I still haven't done my OCing (or ordered fans - something I need to do more research on to find the "right" ones)... But, in addition to the hard drive I added right when I got the computer, I just installed 2GB of PC2700 DDR RAM (Crucial brand). It's CL 2.5, 64x64, Non-ECL, Unbuffered, 184-pin.

What I find VERY interesting is that the System Profiler shows the speed as PC2600-25330. NOT PC2100, which is the stock RAM's speed. So, without even OCing, I'm getting more bang for my buck.

All 2GB after shipping cost me $150 and change.

I haven't actually tried using any apps, but first boot after install was slow (as I expected), and everything is running A-OK. Time to try Photoshop, iTunes, World of Warcraft, user switching, and some other things and see how it all goes.

Next step: Fans and overclocking. (After that? Graphics card.)
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DP 1.08GHz PMG4 MDD, 1GB PC2700 DDR, 200GB ATA (16MB, 7200RPM), Radeon 9800 Pro (256MB)