Win Xp

Hello,
I have just recovered from being stung by a horrible nasty virus called Install_Patch.exe Trojan Downloader win32.bagle.bxn, I was advised by my previous AV provider to have the drive formatted which is what I have had done by a friend and he seems to have reinstalled all the major programs without any problem, I still get the Windows XP updates and support for MS Office which I did not think I would get if the hard drive was reformatted, I have installed Kaspersky as my new AV, I was informed by a friend that I need to have two AV programs, is this correct? I would like to install a Registry cleaner to go with it, what would you recommend?

Thank you