1GB RAM cause crash of vista?

not having enough memory should never caused a crash (assuming crash is a bsod or just freezing). It's more likely due to hardware or a bad driver of some sorts. I've seen a few of your posts so if you've screwed much with your registry or run a bunch trash mod-progs, _all_ bets are off.

re: buy another 1GB ram?
It is much like buying stocks, you may or may not see prices cheaper again and it's pretty cheap now (if you wait, you'd only be seeing pennies savings, if anything). I haven't looked at the next period's ram futures but the article I posted yesterday from Infoworld says that May/June are now lowest for the year... One thing I have seen over the years is that after new technologies come out (i.e. ddr3) old ram prices will go up and stick (look at rdram). If you've got open slots, get a 2x2G kit and up your system to 3G (you will _feel_ the difference and just smile).

good luck

Boot file degradation in Windows usually means you have hard disk issues. Make sure you have plenty of space and back up frequently.

2G will speed up your system and put less stress on your hd. I highly recommend it. However, it wouldn't impact your issue with your system crashing.