I just replaced the memory in my XPS400 with 4 1GB modules.  That appears to have corrected my recurring blue screens.  My computer has Intel Pentium D 820 (2.8GHz) w/Dual Core Technology.  I do a lot of video and music editing.  My DVD burner  (supposed to be 16X) is only working at a very slow speed and used to burn faster.  Is there a way to tell if the hardware needs to be replaced?  Is there an option for upgrading my processor and would that improve performance of my computer?