Try 1uF for MAX232, 0.1uF is for the MAX232A, or MAX202.
(I think in the old days, it was even 10uF)

Be sure of polarity when you use ELCO's.

(see www.maxim-ic.com)

For your SW: Do you need interrupt driven or polled serial comm?
Need circular buffers?

You surely can find lots of code on the net, if not please tell.