There is a danger to this, if you have no backup power supply, as a loss of power would result in loss of any information within the cache at the time of the outage. So.... make sure to continually backup your files in data programs such as Word, Excel, and so on...
To enable write caching:
1. Press Vista Orb/Computer/right click on 'C'/Properties;
2. Click on Hardware and double click on your hard drive;
3. Go to Policies and check 'Enable Write caching on the Disk'
4. You can go one step further by checking 'Enable Advanced performance' but pay attention to the underlying warning.
This option isn't available to all. Newer systems are automatically set to run in AHCI mode through the BIOS and utilize a program called the 'Intel Matrix Storage Manager'. Together, these already enably higher performance of your system and prevent you from 'Enhancing Write Caching' on your own. You may be able to check it off but when you exit and return, its unchecked again. Don't panic!!! Thats just the way it presently works.