Here's a breakdown of some of the major areas that I have experience with. Please realize that I can't list everything I've ever worked with, but please understand that even if it's the latest and greatest new toy that just came out and you need help with it, I can help you figure it out, install it and show you how to use it.
Desktop Operating Systems
Windows 10/8/7 (all flavors), Vista, XP Pro, Tablet Edition, Media Center and Home Editions. As well as Windows 2000 Professional, Window NT4, NT3.51, ME, 9x and MS-DOS.
Server Operating Systems
Windows Server 2012, 2008, 2003, 2000, and NT Server. Novell Netware 3.x, 4.x, 5.x
Dell, HP-Compaq, IBM, Sony, Toshiba, Gateway, eMachines, and custom-built.
Dell, HP/Compaq, IBM
Apple, Android, and Blackberry devices.
Cisco routers and switches. Cisco Firewall Appliances. Nortel switches. Linksys, Netgear, Belkin, etc
Ethernet, Fast Ethernet, Gigabit Ethernet (over copper or fiber), Token Ring, Wi-Fi (802.11, 802.11a/b/g), Arcnet. TCP/IP, IPX/SPX, Netbios/Netbeui, DHCP, DNS, WINS, SNMP
Cisco wireless access points, bridges and NICs. SOHO Linksys, Netgear, D-Link, etc wireless routers, range extenders, NICs, etc. BreezeCom/BreezeNet and Proxim wireless hardware.
Microsoft Office 2010/2007/2003/XP and earlier.
Cisco Call Manager, Unity unified messaging and BARS backup.
Outlook/Outlook Express, Thunderbird email configuration
Citrix MetaFrame XP SP4 FR3,
Microsoft Terminal Services
Internet Explorer, Firefox, Opera Browser config
Microsoft Exchange 2000/2003/2007
Clonezilla and Symantec Ghost imaging solutions
Microsoft IIS (HTTP, FTP, POP, SMTP)
McAfee Enterprise AntiVirus, ePolicy Orchestrator,
Groupshield for Exchange
Connectix/Microsoft Virtual PC
Symantec AntiVirus Corporate and Home Editions
Cisco VPN Client configuration
HP Storage Works DataProtector, Veritas Backup Exec
Attachmate KEA and Extra! clients
Windows Server Update Services (WSUS)
Adobe Acrobat, PageMaker, Photoshop, Reader
Attachmate SNA Gateways
Intellisync, Hotsync, Microsoft ActiveSync and Palm Desktop
HP System Insight Manager, CiscoWorks, Dell IT Assistant
VNC, UltraVNC (server, viewer, remote deployment)
Active Directory and Group policy administration
FTP Clients such as FileZilla, CuteFTP, etc.
Plus tons of other software too numerous to mention ...