Win32 isn't a virus, it is just that the malware is going to work on a 32bit version of avast.
Vundo/Virtumonde are aliases of the same malware.
I suggest you have a talk to my friend google, just search for the Vitro, Vundo/Virtumonde malware family names there are many variants, Wikipedia results in the search will normally have a good description of the malware family name.
