Pentium D sluggish with Win XP, idles hot too - CNET PC hardware Forums

Here are my specs:

Pentium D 940 Presler 800MHz FSB LGA 775 processor
ASUS P5WD2-E Premium Socket T (LGA 775) motherboard
CORSAIR XMS2 2GB DDR2 DDR2 800 SDRAM
Seagate Barracuda 400GB 7200 RPM SATA 3.0Gb/s Hard Drive
Radeon X1800XT 256MB GDDR3 PCI Express x16 Video Card
Windows XP SP2

I should be flying, right?

I don't know what the problem is, but I just built this new machine, upgrading from a Pentium 4 to the Pentium D and things are slow going in Windows XP -- slower than my Pentium 4 ever was and I've barely installed anything yet. The only two programs I have running so far at startup is my McAfee VirusScan and my battery backup program and it easily is taking double the amount of time that the Pentium 4 did.

It's not just at startup up of Windows either. I just installed iTunes and that easily takes 2 minutes to open. Something's very wrong.

Also, I should mention that my CPU appears to be running hot. I originally had an Antec 500W SmartPower PSU and found that I was idling at around 60-65 C degrees!! Ouch! I swapped out the PSU for an Antec 550W NeoPower and now find that although my idle CPU temperature has dropped to about 50-53 C degree at idle, that's still on the hot side for idling.

I plan on changing the CPU fan and heatsink from the stock one that Intel provided to an Arctic Cool Pro 7, but I'm feeling like this may just be a band aid for a bigger problem and I'm not even sure if the fact that everything in Windows XP is sluggish has anything to do with the fact that my CPU is idling on the hot side.

Now I've got four case fans (three 80mm blowing inward at the front and side of the case and a 120 mm blowing outward at the rear of the case).

Any suggestions on what the problem can be? Thanks for any feedback, and please let me know if I should provide more info if you think it will help diagnose the issue.