This program is consistently at or near the top of the list of downloads at CNET downloads. I believe one of the reasons for this is that it combines several PC maintenance utilities into one program. On launching the program, you are presented with a list of seven operations that the program can perform, and you can check or un-check each operation.
The seven operations are: Spyware Removal, Security Defense (prevents spyware from being installed on your PC, similar to the Immunize function in Spybot S&D), Registry Fix (fixes invalid or incorrect registry entries), System Optimization (optimizes system configuration), Startup Manage (allows you to control the programs set to run at startup), Privacy Sweep (erases browsing and MRU lists), and Junk File Clean (cleans junk files such as .tmp files).
After selecting which checks you want to run, you click the Scan button to start scanning your system. Running all these checks took about 1-1/2 minutes on my PC (P4, 2.4Ghz, WinXP). After the scan completes, you can click on Show Details for each item to see the types of problems found. The detail list allows you to check the items you want to fix, or un-check the ones you want to leave. After checking the details (you only need to do this once, the program remembers your selections), click on the Repair button to fix the problems found.
Advanced Windows Care first performs a backup of all changes before doing the repair operation, so you can restore any changes if you find something amiss. The repair operation (including the backup) took about 15 seconds on my PC. That's it - you are done with your tune-up.
This program might be considered adware by some, as it displays a separate window with an advertisement for another of the company's products. I found the ad to be unobtrusive - it did not get in the way of program operation (you can close the window without closing the program if you want). But if you have a problem with programs that display ads, you might want to look for something else; or consider the paid version, which includes more features and disables the advertising.
What I liked most about this program is the ease of use. There is no configuration necessary after installing, and you just have to take a look at the details the first time you use it. It runs fast enough to use it daily or weekly. The automatic backup is good for peace of mind, too. If you need a good all-in-one PC cleanup program, I would recommend giving this program a try. The program is free for personal use, and can be downloaded here - Advanced Windows Care 2 Personal.