Antivirus - Common sense + Virustotal.com
Registry searching/editing - Registry Workshop
Hex editor - 010 Editor
IDE - Microsoft, Cygwin
Compilers - Intel, GCC, Microsoft
Bittorrent - Custom version of uTorrent 1.7.5
Reversing tools - IDA Pro, Shadow Ollydbg + Advancedolly
Virtualization - VMware Workstation
Emulation - Daemon Tools Pro, DOSBox
Network tools - NMap, Nessus, Metasploit, Netcat