Resolved (sort of)
Trojan kept coming back, followed by others (Heur, reader_s, reader_sl, etc).
Full format and fix boot sector, followed by partition delete and re-create, then another quick format, Win XP install... good to go, no recurrence (yet).
Think I'm in the clear. Luckily, don't really store data on this computer and others on network seem safe... whew.