I will not comment on how your build looks, but to make sure everything is running well, you need to BURN IT IN. Dowload and run stess testing programs and run them overnight to make sure your system is stable. Some examples are, in order of importance:
Memtest 86+
3D mark 2006
Ontrack Data Advisor (wd.com)
PC Mark (insert most recent date)
You need a new CPU, that thing is too slow. Get a core 2 duo or Core 2 Quad for that setup. Pentium D's are old, slow and not up to par with your other components. Without a new CPU you are wasting your Motherboard. Buy a MID ATX tower with good reviews, coolermaster centurion series may be worth a look, very good cases with great airflow.