While I am not sure what you mean by "running pretty good," I have found that Windows itself provides useful tools (e.g. defragmentation, disk cleanup) and many others are available free for the download. You might want to look over BC's list of free utilities found here:
http://www.bleepingcomputer.com/forums/topic3616.htmlKeeping your hard drive clean of gunk, and avoiding downloading all sorts of fun/happy applications, doing some routine system maintenance I have found to be a lot more useful than spending money for applications that make dubious claims.
Cheers,
John