Bikenewbie -

I have only been riding about a year myself. I only own a mountain bike (the money thing!). I too put "slicks" on and have completed 2 cross-state week-long tours (Oct 2001, Jun 2002) and been just fine. I have over 1,600 road miles on this mountain bike!

Figure out
1) what kind of riding you want to do (road only, road racing, road & trails, road & mountain biking, mountain biking only,mountain bike racing...)
2)what kind of riding goals you have - for example, if you just want to do some weekend riding, you'd need a lot less bike than if you were planning on doing week-long tours or riding to keep up with the other club members or racing....
3)how much money is in the budget - around here, an entry level mountain bike (a good one, not Wal-mart...) would start at about $500, a road bike at about $700, a comfort bike at about $300

Some suggested reading
1) A Woman's Guide to Cycling (Gail Barnhardt)
2) The Female Cyclist (Susan Weaver)
both are great all-around books that include information on basic bike fit, as well as women-specific bicycling information, which will help you in doing your research

Websites to check out
1) http://www.terrybicycles.com/

You'll definitely want to peruse this forum for information on favorite saddles!

I am sure others will have lots more advice and references for you; I really enjoy coming to this forum for the company of other women riders!

Happy Riding!