Unless I'm mistaken, swap in the 2.2 and 2.4 kernels only gets used when you run out of RAM. So if you are upping your RAM and not upping the number of tasks you run, there would be no need to increase swap. Less reason if anything, but disk space is too cheap to make it worth repartitioning downwards.
You really need to know how much of ram and/or swap you generally use. With Windows NT/2K, the Task Manager's Performance tab tells you this (Commit Charge, Total used currently, Peak used overall, and Limit of ram and swap together). How does one determine this with Linux? ~mark