I just saw your PAExec.
Personally I have moved on from PSExec to WinRM/WinRS, and I would also recommend this to others. (Only Windows 2003/XP and above).
My next big step in my sys admin career is to move from batch files to PowerShell, which also supports remoting over WinRM. I managed to convince my boss to treat me to a three day course of Powershell for administrators, yummy...