Symptoms like this indicate a fragmented hard drive, or a lot of processes running at once.
Judging by the fact you can overclock, you probably already know how to defrag, and how to check how much of your system resources are being used up.
There is also a possibility that if you have a lot of things on your desktop, you will have slow response.
Intel E6750...........PSN: ELBATROP
XFX nForce 650i Ultra
Patriot PC2-6400 8GB (4x2GB)
36GB WD Raptor
Samsung SyncMaster 931c
Samsung SyncMaster 750s
Windows 7 Home Premium 64