OK, I know you've all probably heard this before, but I just added 1GB of RAM to a stock 17" Intel iMac (512MB), and it makes a huge difference. If you were thinking, "aw, is it really worth it? I'll just get by with 512," think again! 10.4 gobbles RAM, Rosetta gobbles RAM, Safari gobbles RAM, etc., etc. Try having an Office app open, your e-mail client, and, say, your main work app (i.e. Flash, Photoshop, Xcode, etc.) And don't forget all those fun Expose widgets--they may not be visible all the time, but they still want RAM. Just do it. Got to get that RAM. Go on. Buy it. It's calling you.