Try something like a 20 buck USB audio adapter. Example at http://www.amazon.com/Headset-Buddy-Adapter-Convert-Computer/dp/B0030E9FKO/
If you only need Mono, look at the 3 buck devices.
Remember that your laptop can be fixed but at many hundred more dollars.
I have a dell vostro 1500 and when I record, either from an external mic or from system audio the playback has a terrible static sound which is like a constant hummmmmmm and it almost drowns out the actual recording.
How do fix this??