SSDs have been in a range of laptops for a while, in a range of form factors. The largest notebook drive you can sensibly get (i.e. afford) is 128GB or 160GB. The largest you can get in any form factor is 640GB, I believe. Compared with hard drives, they have no spin-up time, no head seek time and generally higher bandwidth. They're a little lighter and consume less power. Some early designs are a bit sucky on random writes. Flash may have substantially shorter life, which is one reason SSDs are not going into servers right now.