She may or may not need women's specific geometry, even if she's small. You should take her to test ride some bikes, see what she likes, what fits, and go from there. Have her try some different materials. Lots of us still love steel (and carbon, and aluminum). The best deal will probably be a complete bike, unless you already have a bunch of parts that will work for her. Remember, she may need lower gears than you do if you've been riding a long time, and shorter reach brake levers and shallower handlebars if she's small. Also, some shops sell used bikes, so that may be a more affordable option.
Hope she chimes in. There's a lot of good info on this forum. Good luck!
ETA: It could take years to find the right saddle, so don't expect the one you use will work for her. It could hurt her.
Last edited by redrhodie; 02-13-2011 at 07:17 AM.
'02 Eddy Merckx Fuga, Selle An Atomica
'85 Eddy Merckx Professional, Selle An Atomica
'10 Soma Double Cross DC, Selle An Atomica
Slacker on wheels.