1. XP doesn't use config.sys
2. Dell will sell you replacement restore CDs. While it may seem odd, it's all part of the same issue of what happens when you lose your car keys.
Tell more and get that CD on its way. Given the cost of blank CD's, I'd make a copy for that rainy day.
What is a person to do when Windows XP won't start? My daughter has a Dell Dimension that comes up with a message that Windows can't start because config.sys is missing. She has not been able to find the Dell restore CD and apparently Dell was no help.