Try an Intel SSD before saying that it isn't worth......
It's only a matter of personal need of storage and personal budget....in other words, it's only a matter of WHEN you're gonna buy one...
An Intel SSD disintegrate your HDD in every possible way and in every possible activity beside...storage space. But for storage space it is possible to use a fw800 bus-powered hdd. Or an HDD in a MCE Optibay.
Personally, I will wait the Intel x-25m 160gb to get below 300 (in Europe now it costs 400) and then get it immediatly....finally we are out of the "experimental and hassle" phase of the SSDs and everyone should approach this wonderful technology as soon as possible....it's the SINGLE best performance upgrade (in everyday usage) of the last 5-10 years....it eliminates a long-hated bottleneck of our machines...
I like Uberamd's personal choice to get the 500GB drive, I agree with him but maybe for different reasons. While I can see the speed benefit by going SSD, I'm one of those types who HAS to have everything on the internal drive, externals attached via FW, just need to then back that primary drive. I hate having crucial information on separate drives, and at the moment that is what I would have to do if I purchase an SSD due to capacity restraints.
The price has to come down, and the capacity has to jump ahead of what I have inside my laptop right now, which is a 500GB 7200rpm drive. Until then I'm not playing, but happy to wait anyway.
At least further down the line I can still extend the life of this machine by buying an SSD, saving me further money.