Things missing from your post:
1: Model name, eg: Dimension, Latitude, other?
2: Desktop or Laptop?
3: Dell service tag number?
In checking the Dell website, I found no listing for xts450. Visit the Dell link below and search for bios update for your unlisted model.
http://support.dell.com/support/down...=us&l=en&s=gen
Note: Dell pc's require bios updates from Dell. There are no others to choose from.