Cheryl, please post back and let us all know if the "tuneup" significantly improves your computer's performance.
Dell is a very good brand of computer, and whatever Vista's annoyances, people do use it without problems. So if you still have problems, we can work on them.
Craftiladi makes a good point about the Vista. I would say after you've done the virus and spyware/adware downloads and scans (and before defragmenting), check for Windows updates to get any patches for Vista that you don't yet have. It may be that your computer is set to check for them and get them automatically, but it's worth checking anyway.
Lostn51, VERY important point! Though I thought you ground yourself to keep from getting a killer shock, not to protect the computer.
Stitchnripper, everyone I've ever known who's owned a Mac has been totally smug and superior about it. They never complain, never!