Not sure on your Audacity issue specifically, but the thing that improved my timing massively and very quickly was when I bought my first looper. (Boss RC-2)

Being able to record my own backing tracks, even if it's only two chords to solo over, with built in drums and loop quantisation (sp) that automagically puts everything in perfect timing helped me sooooo much. After a few months jamming with the looper you WILL improve timing.

Jamming with others will also help a lot, as long as you have a drummer who can keep time of course!

I've since moved on to a Boomerang 3 looper which doesn't automatically fix your timing, so I've had to become even more aware of my timing to make great loops.

If you don't want to splash the cash on a looper (but do, seriously, they are one of the best guitar training tools ever) play along to backing tracks. They are readily available all over the net and are a lot more fun than the last resort, which is using a metronome.