Before you go nuts on me hear me out.
There is a know compatability issue with Vista and 4 gig of RAM whilst installing. You need to take out 2 gig of RAM and do your install. Once all is up and running there is a MS fix for the issue. Run that fix and then you can install your other 2 gig of RAM.
I know it sounds freaky but it's true. Give it a try.
Here is the MS hotfix for when you get your system up with the first 2 gigs.
I had windows xp installed on my computer, but I bought windows Vista ultimate. I tried installing vista and everytime it gets done intalling it says it is going to restart, I let it. when it comes on and tries to start it briefly flashes a blue screen and before I can read the error it shuts off. I thought oh ok well I just did something wrong let me try it again, so I do and the same thing happens. what can I do? oh I have 4gigs of ram, athalon 64 x2 processor, 500Gb sata HDD, eva 8800 gts 640Mb, so I know my system should be able to handle vista 64 bit. please help me, thanks.