Hi Karita –
A few things can be done routinely:
1) Windows Updates. Very important, especially for Windows 7 machines (there aren’t too many updates released for Windows XP at this point). Windows should do them automatically, but it’s usually worth checking from time to time just to make sure. There is usually a shortcut to Windows Update in the Start Menu.
2) We also like to manually run scans from these programs on all PCs:
Both are free. Always a good idea to make sure machines have up-to-date versions of Microsoft Security Essentials (Anti-Virus & Spyware):
3) Removing old and unused programs is also worthwhile on any PC, but since your workstations shouldn’t have much software on them anyway, I can’t imagine what would ever accumulate in the first place.
4) The Macs are mostly self sufficient. Software Updates are always a good idea (Apple Menu->Software Update). Also leaving the Macs on overnight at least once a month will allow all of Apple’s built-in maintenance scripts to run automatically. If they’re always shut down at night, they will never run (the scripts do trivial maintenance like clear old logs, cache & temp files, & check system files for consistency & corruption).
5) Defragging Windows 7 & the Macs is completely unnecessary. I’d say it might improve performance on a Windows XP machine by about 1% at best. Defragging was important in the days of Windows 95 & 98 when Microsoft was using Fat-16 and Fat-32 file systems. Filesystems like NTFS and HFS+ (modern PCs & Macs use these) are not commonly susceptible to fragmentation.
6) You could also encourage users not to do dumb things like download ‘free’ software, screen savers, file sharing programs, and use Facebook. All of these are known to be severe sources of viruses and spyware. Most security breaches we have seen lately are the result of a user-initated software installation – not something that any security software is going to prevent.
Hope that helps for now –