Dual booting XP and 7 is the issue or an incompatible device like USB printer/hub/etc.
Install the 7 Drive stand alone. I have a 5150 with windows 7 pro and its fine. I would also DISABLE hibernation since this is the cause of some issues and if it has 4 gigs of ram then disable the page file as well.
You haven't enumerated all the hardware involved or what the crash is specifically.
There are Zero Issues with the 5150. Incompatible ram is possible. Are all the ram modules the same vendor and speed?