pc2700 regular kingston would be fine for you situation (without heat spreaders), go at 1gb, really. more than that and you're probably really not going to get any benefit, even running lots of hefty apps and games.
if you're not overclocking, you probably really don't need the heat spreaders.
was going to get some corsair xms 3200 in my system i just ordered, but i decided to save some cash, so i got a good deal for some kingston hyperx 2700 512's, and they came with heat spreaders. i'm pretty happy with it, haven't oc'd the system much yet, but the memory seems pretty good. it's only like 10-15$ more than regular kingston ram. plus, they have some of the nicer looking heat spreaders
depends on what you game in, but my new system with a 2400+ (currently at 2.13ghz), 1gb kingston hyperx, and radeon 9700 pro 128 will run ut2k3 flawlessly @ 1600x1200x32, whereas my 2000+ with 512mb 2100 would not (same video card). in fact, it ran it pretty poorly, and level changes took forever. now it pretty much runs like the old ut. i also dropped the wd 8mb cache hdd's in, so that makes a bit of speed difference for loading as well. it will be a tad slower if you don't have that
hope that helps.