a full wipe like that wouldn't hurt the drive and would help you get rid of your virus, however I would think that it's probably not any different than doing the "slow" format of the drive where it validates that there aren't any bad sectors on the drive by writing info and reading it back.
there is an information area about the drive partitions that might get flushed better with the special program.

as for the virtus checker, I personally use Avast only because they were one of the first to claim to run on x64 and they have a freeware version.
I'm not that big of an internet browser kind of person so I'm not sure how great this checker is. ( I browse here and a couple of the wow sites, semi safe if you ask me ) and I have a blizzard authenticator so I can care less about key loggers on my wow accounts.
I had my yahoo email hacked into once but that was because I had open wireless and no local pc passwords on my LAN, once I disabled the wirless and placed passwords I've not had any problems since.