Reply to advice for recording

Hi guys I'm wondering which software to use for recording Traktor mixes made with an external mixer.
I thought of using an old laptop ( pentium m 1,6 ghz, 500 mb ram) for recording mixes through the record out of the external mixer. I thought that maybe someone who`s into production might have some advice on which good freeware (audacity?) to use and which pitfalls to remember (how do I set the correct level etc.?)
THANKS!