Perhaps a look at this thread will help:  XPS 410 Processors.

You're welcome.

True, the thread was started about ten months back, but the machine in question is a design more than four years old.  I don't think Intel is making too many new processors that support the LGA 775 socket.

Best of luck to you!

Thank you for the reply. I had seen that list before but was pretty old so didn't know if was updated. May have try out Intel Core 2 Quad Extreme Edition QX6800 2.93 GHz see what improvement it might be. I'm currently running 2.4 ghz dual core 6600 Conroe. Just trying keep up with times without whole new computer as this one has been pretty good to me. Was hoping to get a 3.4 ghz or better but guess going quad with a 2.93 be ok.

After pricing that processor I'm not sure that's gonna be my choice. Maybe I will price another off the list. There are quite a few lg775 socket processors the problem is with getting the bios for them on Dell mother board from what I hear.