Computer is slow, frozen, dead, and garbage?

toshiba satellite laptop sucks. worst ever! had vista home on it. kept crashing freezing and had the worst battery life ever! (45 mins) brand new. so i put ubuntu on it. never had a problem with ubuntu before. got 8.04 and now firefox keeps crashing repetitively. whats wrong with it? what are some good laptops to buy? i NEED a dependable one for college