Upgrade processor?

[idata]

I have an older computer that I'm looking to possibly get a new processor for. It is a Dell Demension 9100 (http://support.dell.com/support/edocs/systems/dim9100/en/D86630LRs.pdf http://support.dell.com/support/edocs/systems/dim9100/en/D86630LRs.pdf for basic information). I recently updated my power supply to a 400 W (but I'm looking at getting a 500 W if it's required for a decent processor upgrade) and I put in a NVIDIA GeForce GT 240. The current processor is an Intel Pentium D 2.79 GHz, the system has 3 GB of RAM, and I'm running Windows XP and Ubuntu 10.04 on it. Is there an Intel processor that is better than what I have that I can order and put into this system.

By the way, I know people will probably tell me to get a new system (which I plan on), but I'm not looking at playing Crysis 2 or anything on this particular one. I'm just wanting to give this one a little boost, because it's still running nice and smooth.

If there's any other information I need to find about this system, let me know and I'll provide it. And again, if the power supply is a limiting factor, I'm willing to get a stronger one if need be.

Thanks for any suggestions.

P. S. - I've not upgrade a processor before (been too scared too), so if I get a new one, I may need help making sure I don't fry anything.

Edit: I have done further research and determined that there may not be any processors that I can upgrade to with this motherboard. My next best option is to find a motherboard that can take a stronger processor, but have all the slots and such that I need for my hardware. The link above has a layout of the board and all of it's slots. Is there a semi-sane way of looking up motherboards that will suit my needs and processors that would work with them? The motherboard is a Dell 0X8582 in case that helps with figuring this all out.

[Adolfo_S_Intel2]

Please contact the computer manufacturer, in this case DELL*, so they can provide you a list of fully supported processors for your DELL* system.