You need to nuke the machine and reload it. This should be trivial for a business machine, and if it isn't then you currently need to fix things so that it is trivial in the future. Leaving aside the issues Evan raises (and which I totally agree with), it's also often the most effective use of employee time - it can take a long time to "clean" an infected machine to the point where you're 99% certain it really is clean (and then there's that 1%...) and the time to do re-load your standard image will be shorter, at least in terms of admin time needed.
Also, and just as importantly, you need to figure out where the infection came from, how it eluded whatever AV/Security precautions you currently have in place and what you are going to do to lock things down and prevent it happening again.