Yep, Vista's a resource hog. However, I've found that the footprint can be substantially reduced by disabling redundant (and in some cases, pointless) services that I don't need.
The worst example is the Tablet Input Service (presumably required if you have a touch screen laptop) which is enabled by default on my desktop PC. How much effort would it have taken to stick in some code to just f*cking CHECK if the system has a touch screen before enabling this service? It's simply bad design.
Other services I disabled are the Diagnostic Policy Service, Distributed Link Tracking Client, IP Helper, Messenger Sharing Folders USN, Journal Reader Service, Network List Service, Offline Files, Readyboost (unless you like slow memory performance), Remote Access Connection, Server, Windows Error Reporting Service (very annoying anyway), Windows Image Acquisition (WIA), Cryptographic Services, IKE and AuthIP, IPsec Keying Modules, IPsec Policy Agent, Network Location Awareness, Program Compatibility Assistant (I can figure it out myself if it didn't install right, thank you!) and Shell Hardware Detection.
The result is that I've freed up memory and CPU and now have more resource to run the things that *I* want to rather than what Microsoft wants me to. And before you ask, everything that I want to use still works fine!