Been playing with an Intel 80gb SSD (Solid State Disk) drive for the last few days - cheapie $229 one, not the high end one w/ extra cache.
The tech blogs are on-target when they say that the difference isn't that apparent but swap the old rotating platter drive back in and you'll think something is wrong! The difference in lag time is unreal - it just barely exists. Drive "runs" cool to the touch.
Boot time on a Dell dual-core 2ghz w/ 2gb was only a few seconds faster; but as soon as the desktop is up you can instantly open MS Office and it's right *there* in 2-3 seconds. As a test, added IE8, Firefox, and MS Word to the startup group - all 3 open and ready in 4 seconds from clicking "ok" at the login prompt. Power on to no-lag usable is 20-30 seconds faster than a Core2Duo with a 7200rpm SATA drive.
Swapped the drive into a single core P4 3ghz system and ran just about the same as the dual-core.
There will be some issues down the road with the flash being "used up" prematurely by the way current OS's utilize disk space.
$230 for 80gb may be expensive but I still recall Rodime 20mb full height MFM drives for $1500, and thinking $279 for a 340mb was a steal