I did my first triathlon at 46. Here are some random thoughts for you...

First, start small. Find a local sprint, something where you know you can do the distances. That takes the stress of being worried about the distance out of the equation. Smaller races are less intimidating, too. Some women also prefer a women's only race. Look around your area to see what's available.

There are age groups. They generally run in 5 year groups (20-24, 25-29, etc). Prizes will be given for the first 3-5, depending on the race, in each age group.

Transitions seem intimidating. If you're methodical and practice, they're no big deal. (I can get into that more if you want.)

If you get to a race and are confused, the volunteers are very helpful. Don't be shy to ask questions.

As far as your running goes, start slowly and see how your feet feel. That's the only way to tell how you'll do.

Don't worry about a fancy, expensive tri bike. Lots of people do tris on mountain bikes, hybrids, etc. No one will give you any grief.

Triathlons are a fun challenge, and addictive. Mostly people are very supportive.

One other thought... check out www.beginnertriathlete.com. It's a great resource with lots of good articles on getting started and going on from there.