Dell Reinstallation CD for XP Home Edition

My computer has become pretty much unusable due to two pieces of malware (TR/Drop.Pincher.aek and TR/Dldr.Mufanom.ldg) and a damaged DLL (wzcapier.dll). I suspect that I will have to reformat the hard drive and start over. My question is, how do I do this? When my previous computer (IBM Aptiva) needed this procedure, there were instructions with the computer and a Product Recovery disk that reproduced the programs that were on the computer when I purchased it. That appears to not be the case with my Dell Inspiron. What I do have is the following: Dell Reinstallation CD for XP Home Edition, Service Pack 2 Dell Drivers and Utilities Already Installed on Your Computer (CD) Microsoft Works 9 (CD) Roxio Creator DE 10.1 (CD) Dell Application (Cyberlink PowerDVD DX 7.0 Software for DVD Playback (CD) My main question is, what will the Dell Reinstallation CD for XP Home Edition do? 1. Does it only overwrite the existing Operating System? This would mean that all of the data files, etc. that I have added to the compter since I purchased it would still be on there. 2. Does it automatically reformat the hard drive and then reinstall the Operating System? This would mean that all of the data files, etc. that I have added to the compter since I purchased it would be erased and that I would have to get copies from my most recent backup. I should mention that I my backup isn't as recent as what I would like it to be. Help!