Set up your computer for video editing
Right click on the My Computer icon; go to PROPERTIES,
Click the ADVANCED tab and then the Performance SETTINGS button;
Click on the Advanced tab;
Click on Virtual Memory Change button,
Set a custom size of the amount that is recommended on Virtual Memory screen "Total Paging Size For All Drives" bit (about 1.5 times your RAM amount eg 1500/1500 for 1gb of RAM), and preferably on a partition/drive that is not your Windows drive. If both the values the same, the Paging file will not fragment.
If you can, put it at the start of the drive with your defragging program.
Make sure your hard drives are running in DMA mode. Running in DMA mode will minimise dropped frames during video capture.
Don't run other programs while capturing, encoding, or burning.
Some other good tips for speeding up your computer are here:
http://www.blackviper.com/WinXP/supertweaks.htm