Forgive me if this has been covered elsewhere in the forums...but how difficult is it to get involved in cyclocross?

I'm fairly certain my commuter would make a reasonable beginning cyclocross bike: 2011 steel chromoly Marin 4 corners. If I put it on a diet to lose panniers/fenders, etc, I think I could get away with just throwing STI shifters and cyclocross tires on it (more than enough clearance). Might be a few pounds heavy, and the tube shape is not ideal....but I don't plan on winning anyway.

More importantly....I stopped by the first cyclocross race in Chicago this year very briefly and saw a race or 2, one of which was a cat 5. It doesn't LOOK that hard....is it possible I could jump into a cat 5 race with no racing experience of any sort and not make a fool of myself?

I commute/ride weekend rides maybe 300 miles/week, planning on getting back into winter riding this year after a long hiatus after child was born. I can keep a decent pace, I've gone on a couple fast paced road bike training rides. I kept up, but decided that serious road riding just is not my cup of tea. The people/atmosphere at the cyclocross race was much more in line with how I view cycling....have fun, push yourself if you feel like it. Not, max spandex, min weight, max pain.

This is a very long winded way (sorry) of asking: can I just show up to a cyclocross race and expect to enjoy myself? Or is cyclocross really just for seriously competitive current road riders.