Probably you can't do this without the cooperation of your IT-staff. They will have to open ports on the firewall or install vpn-software or whatever security measures they think necessary.
So let them determine the software to be used also.
The best way, by the way, is to not use any local software. If all your applications are webbased (like Gmail, Google docs and Salesforce.com) there's no difference at all between working here or working there. Just log in from whereever you happen to be.
I would like to be offsite and be able to access my computer back at work and also have my laptop to act as like im actually sitting on the network at work.
What is the best software for me to be able to be offsite back be able to login to my network as if i was actually at the office?