I guess alot of us have tried it, but i did a test with like a 30 second clip and kept going and going seeing how many i could record.....i gave up somewhere in the 50's......
In testing out my new 2.5Ghz DAW, I loaded up 35 full-length stereo 24-bit/44.1kHz tracks (approx. 60Mb each) and they played by effortlessly with the CPU meter only hitting 10%.
You'll probably run out of CPU steam from plug-ins and soft synths than from track count on most PCs nowadays....