That will depend on just what files are being seen. The system restore points are compressed along with other things. If the files are in folders created by you or 3rd party installers the option to delete will depend if those are zip files you downloaded or something needed for an installed game or app.
A freeware for seeing a drive cleaned up removes all now useless temp folders plus other clutter from a drive. The CCleaner also nick named "crap cleaner" is found at http://www.ccleaner.com/ That will also clean up all offline IE content if left checked off as well.
Until you know precisely what files are being pointed to you simply don't rush to delete them and find you deleted something you wanted to keep! Be smart and first browse to where the files are located to see if any are simply being stored in a separate folder like family photos rolled up in a zip file or an update you have onhand.
Once you have confirmed none are wanted simply send them on their way. The main problem seen with automatic removers is grabbing at any file not associated with a program installed at the moment.
Often times you will find them listed under "DocumentsandSettings>user name>Local" or another MS created folder if those are simply clutter left over from uninstallers, the original Windows installation, or old restore points that haven't been automatically deleted when new ones were made. If you see the file names you can easily run a search by using that option right off the Start menu bar if the full path isn't seen.
there's a file in the temp folder called ycomp_setup. It's an application file and the date modified is 1/09/2007. Can I delete this item? It is 1.6 MB in size.
That might effect an uninstaller since a 3rd party app placed that there. But other then that it's not part of Windows and can always be replaced by simply reinstalling the same program if needed. Other then that it shouldn't be anything you have to keep.
The CCleaner tool linked before is also good for cleaning now useless empty temp folders to free up drive space. Just remember to uncheck the IE history to prevent the need to re-enter user names and passwords if you want to retain them.