Handy bike guide:
3-5 year old: 16"
5 and up: 20"
Small adult: (around 5' to 5'6") 24"
Large adult: 26"
XLarge Adult: 28"
If you're 5'5", I'd do a 26" with the seat lowered. Larger bikes give more room to pedal, so most are more comfortable on a larger bike. A good size guide is you should be able to sit on the seat and you should be able to fully extend your legs so your feet are flat on the ground. Hope this helps.
I'm suprised we haven't gotten any "bike snobs" (as I call them) yet. Everytime we get a nice bike deal, some jerk comes on and starts spouting off about "I wouldn't put MY kid on a cheap department store bike...it'll fall apart and he'll get killed. You must spead at least $400 on a useable bicycle..." etc.
Nice deal. I just got my 3 year old a 16" that I'm going to put together this weekend at Walmart. (He's very tall for his age). I think I paid a similar price. It's a Huffy and had a metal framed hand brake as well as coaster brakes.