As far as the Vista upgrade goes, I doubt it'll make any difference. You have to go to the second tier of Vista to be able to get things like Aero, which is about the only promised feature that actually made it into Vista. Otherwise, it's XP with IE7 and some post-SP2 updates all integrated in... Basically, it's Win98 all over again.
Also, you have a 32-bit OS. It's real easy to tell, since only XP Pro was ever released as a 64-bit version, and you had to specifically request it be installed, or do it yourself. Vista will come in both 32 and 64-bit flavors, and you're free to pick whichever you want. The 64-bit version will have a few additional features as related to high resolution video playback. But if you don't have a 1080i HDTV set and plan on getting either a HD-DVD or Blu-Ray DVD player and 1080i content, then there's probably little benefit to the 64-bit version.
ver.5.1(build 2600.xpsp.060200-1751 service pack 2)
Dell says it's 2005 MCE. System info says XP Pro-sp2
Will be upgrading to Vista shortly. Also, how do you tell if it's 32 or 64 bit system? I believe it says X86-based PC. My CPU is AMD 64x2 4200 Live. I just want to be sure I do proper upgrade. Thanks