Brian,
Another vote here for fixing up the twenty. It's a perfect upgrade platform and you can do it for less than a speed pro, even if you have a bike store do all the more time consuming mods. The original conversion for me was new cranks and bottom bracket and a SRAM dual drive rear hub. The whole thing, including the rear wheel build done at the shop, was about $425.00 .
I have obviously done more upgrading, however the first ones were the most important, IMHO. If I had it to do over, I probably would have kept the original fork. I'd put it back on, but have moved and can no longer find it.
Juan