Monitor Settings Help

I recently reformatted my computer due to a virus...i reinstalled Windows Xp and when i set it up and everything the screen resolution was too small and it was set at 800 x 600...before i reformatted the computer it was 1024 x 768. Now it is at 16-bit...and the size of everything is too big...I went to control panel--display--settings--and i tried to scroll the bar all the way to the right to try to get 1024 x 768 and it says it is a default monitor type...even though I have a dell monitor...I am not sure whether its an adapter or w/e...but I am not sure how to fix this problem...please anyone help methe type of Computer i have is a Dell Dimension 2400 and the type of Monitor i have is a Dell E151FPp....so with all this information I have provided...I would really appreciate if anyone would give me a solution to my problem.