Yes, a clean install of the OS (prime time for Vista x64) would be the way to go along with freshly loaded latest drivers for all devices.
Speaking of which, did you do a clean install when your switched to a new mobo and the E6420? If you didn't then that's where your trouble is.
You can not switch between different chipset(when switching mobo) without a clean install of the OS. Most system would just BSOD if you did that.
Well my uncle gave me the CPU/Mobo and the way he installed windows was, he had another hardrive with windows installed on it already and he transfered it all to mine. He said his harddrive had windows installed with the same CPU/Mobo I'm using now. Would that still cause a problem?
I'll update on the HDTune test when it's done.
Here's the benchmark
HD Tune: Maxtor 6L300R0 Benchmark
Transfer Rate Minimum : 1.3 MB/sec
Transfer Rate Maximum : 1.7 MB/sec
Transfer Rate Average : 1.6 MB/sec
Access Time : 18.3 ms
Burst Rate : 1.7 MB/sec
CPU Usage : 53.5%