One of the first things I normally do when I set up a computer with Windows XP, right after I install anti-virus and anti-spyware programs, is to configure Internet Explorer (IE) and System Restore (SR) to use less disk space than their defaults. Typically, IE only needs 80 MB of space to cache files, but by default uses a lot more. That adjustment is found at Tools/Internet Options/General/Browsing History One of the first things I normally do when I set up a computer with Windows XP, right after I install anti-virus and anti-spyware programs, is to configure Internet Explorer (IE) and System Restore (SR) to use less disk space than their defaults. Typically, IE only needs 80 MB of space to cache files, but by default uses a lot more. That adjustment is found at Tools/Internet Options/General/Browsing History/Settings in IE 7.Figuring out how much space SR needs is a little trickier. On Windows XP, each restore point is typically about 100 MB, but is compressed to about 50 MB. The restore points back up key system file and registry changes, and help protect against accidental and malicious damage to your system. They are kept in a hidden system directory on the system drive. On one of my machines, that directory is C:System Volume Information_restore{EC68CA24-6F61-45D4-9AB4-0D8E806BC2E3}. The last section of that is a machine identifier, and can be found in the registry at HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionSystemRestoreCfgMachineGuid.How many restore points do you need? Windows XP generates one restore point a day, plus restore points for major installations. If you need to go back 5 days, then 10 restore points should cover you quite nicely, meaning that you need about 500 MB of disk space for restore points. I typically double that for comfort, and allow SR to use about 1 GB of disk space on the system drive, as opposed to the default of 12% of the drive, which is 19 GB for a typical new 160 GB drive. 19 GB of disk space holds almost 400 restore points. Does it make sense to have restore points going back 6 months to a year? I don’t think so. I go to the System Properties control panel, pick the System Restore tab, open the settings for the system drive, and drag the slider as close to 1 GB as I can make it.What about SR on Windows Vista? It turns out that Vista not only keeps restore points, it also stores shadow copies of files, so that you can recover an old version of a file that has been corrupted as well as restoring an old system state. Vista allows SR to use up to 15% of each NTFS drive on the system that is at least 1 GB.On Windows Vista, you have a certain amount of control over restore points, but not nearly as much as on Windows XP. You can open the System Properties control panel and pick the System Protection tab after verifying that yes, you really, truly, cross-your-heart-and-hope-to-die want to do this. There you’ll see a list of drives that can hold restore points, along with the date and time of the last restore point on each enabled drive. You can turn System Restore off or on for a drive, but there is no user interface for adjusting the SR size. There is a registry entry for the DiskPercent that defaults to 15. It’s probable that adjusting this value will change the maximum amount of space used on all enabled drives, but I haven’t done the experiment. I also haven’t determined whether adjusting this registry entry is a safe thing to do. If Microsoft has documentation on the subject, I haven’t found it.What I do know is that quite a lot of disk space can potentially go to restore points on Windows Vista. I’m guessing that the 24 GB that can be allocated from a 160 GB drive is enough to hold restore points and shadow copies of files for about 6 months. Does that make sense to you? Software Development