I'm able to make 120GB work (barely). 250+ GB seems pretty decent for a main drive especially if the prices keep going down. I've had some issues with my Corsair drive so I'd probably go with an intel SSD on the next upgrade.
Honestly 180GB isn't that bad for a main drive, especially for that price. I use an SSD as my main drive and two 2TB hitachi drives in raid 1 which works well. I also backup my main drive to the mirrored pair.