The first 3 BCCode's (STOP code's) point at a driver issue when accessing memory.
The last one points to a timer issue with a secondary core in the processor.
I'd start by disconnecting all external devices and seeing if that stops the BSOD's. If it does, then plug them in one at a time until they start again.
You may also want to run the Vista Memory Diagnostic (link here:
http://www.bleepingcomputer.com/tuto...torial146.html )
Finally, did the shop tell you why they wanted SP1 off of the system? This will leave you vulnerable to exploits that SP1 is supposed to protect against.