I'm bidding low, in order to get good Freelancer.com reputation.
Sounds like its something easy to do. Do you have the source code or just the exe (it can be "re-engineered" unless it was "obfuscated" which means that it won't be easy to reconstruct).
Can you say what the current program does? (not what you'll be using it for)
That will help all of us give you a better estimate of time (and budget).
I'm in Israel, GMT +2 (google Jerusalem time zone to see my hours) and do not work on Friday and Saturdays.