Jeez guys give the OP a break ...
I just asked about the forumz there as I know diddly bout Dells.
The processor upgrade you are suggesting would not result in a discernable difference in the experience though.
http://www.techspot.com/review/53-pentium-e2140-e2160/
Pentium E2200 (2.2 GHz) with 800 MHz bus and 1 MB shared cache in the second level. It is based on M0 stepping Allendale core.
The Pentium E2180 (2.0 GHz) and Pentium E2160 (1.8 GHz) is just a tad slower.
If the bios will support a faster 65nm cpu then I suggest you look for an E4700.
I say that because anything faster requires a 1066FSB and I am not sure if your mobo supports faster than 800FSB.
Hope this helps.
http://www.intel.com/products/processor_number/chart/core2duo.htm