I'm running a version of Vista Home Premium SP1 that I created with vLite 1.1. Cutting out most of Vista's bloat sped things out a lot. Use a good defrag program like Perfectdisk that defragments the hd using the data collected by Vista's prefetcher will help. It doesn't hurt to to have a 7200 rpm hd also.
Always install the latest versions of software rather than install whatever version you have on hand and then update. Getting rid of the useless crap that Dell pre-installs on new computers will help speed things up also. You'd be surprised on how much junk is running in the background.
As mush as Vista tries to accommodate older programs. There are some programs that just won't work well in Vista. You'll have to live with the consequences if you insist on running them.
Adding another gig of ram will help.