OK here is the deal, getting a new xps 435 box to primarily run CS4 Photoshop the old 32 bit two core is getting a bit tedious on some of the very large files I work with. I run a number of the distributed apps in background all the time, CPU’s essentially loaded 100% all the time, computer is on 24/7. The old Dell has put up with that quite admirably save the fan noise (pretty loud) for the last 5 years or so. But the new wee beastie from what I can see is a bit hotter tempered. Even though I am not going anywhere near over clocking, if I even could with the Dell board, is it really worth the extra coin to put one of the high performance CPU coolers on? Is the CPU going to last effectively any longer, given the reduction in temp? Of course, is Dell going to get their tweeds in a knot about warrantee? Finely I have to assume that these things aren’t rocket science to install, I have put a hard drive and some memory in the old box, are these things more or less plug and play?
The Dell with a stock cooler (no overclocking)... you will be just fine with your system. The Core i7 runs a little hotter than the Core2's did.
CPU coolers arrange for easy to hard to install. Most GOOD CPU coolers will require you to remove the MOBO to install, since they require a backplate for installation. Your system will run cooler with one but with no overclocking it isn't going to make the CPU last any longer.
If you were overclocking, than I would say YES for an aftermarket CPU cooler but in your case stick with the stock cooler.