Ok I'm set on the 7200 320gig WD Scorpio Black.

After doing some research it seems to be a no-brainer because Seagate quality seems to have gone down the drain and have terrible customer service + their 2.5" hd's produce more noise and vibration. Pity, because they seem to perform very well. The Hitachi 7200rpm notebook hd's run much hotter. Searching on thinkpadforums also suggests that the Seagate's have more compatibility issues.

I was torn between 5400 and 7200 with WD because it's only something like a $13 difference on Amazon between the two, but didn't want extra heat and lower battery life. But I found this. The faster drive (with double the cache) is quieter and uses less power, go figure.

I don't actually need a 320gb hd, but it's cheaper than the 250. There's no such thing like having too large a hd and having a lot of it empty, slowing things down is there? I'd guess not, but don't want to find out about something like that after getting it.