Just curious... How long did it take to get the green card once you got the H1B visa?
Asking someone else is not useful to you, because there are several buckets into which one can fall, that have different waiting times.
As I understand it, there are two questions of timing: how long will an applicant have to wait until given an immigrant visa number, and how long will it take to turn the immigrant visa number into a permanent residency. The latter is, I believe, consistent across buckets but varies over time, depending on the wheels of bureaucracy. It's a year or two, I think? The former, however, depends on your level of training and country of birth.
The wikipedia page is pretty good, in particular a few sections:
http://en.wikipedia.org/wiki/Permanent_residence_%28United_S...
http://en.wikipedia.org/wiki/Permanent_residence_%28United_S...
In the latter, note the difference between EB-3 and EB-2, and note the bolded footer (b).
EDIT STARTING HERE:
Oh, this helps too:
http://www.travel.state.gov/visa/bulletin/bulletin_5885.html
Depending on country of birth, if you have a BSc you're looking at 5-11 years of backlog. If you have a higher degree or 5+ years of "progressive" experience you're looking at 0 years of backlog, except 5 years for Chinese and 9 years for Indians. If you are doing family-based immigration, some category/nationality combinations are only just getting around to applications created in 15OCT98 (Philipinos and Mexicans are worst off here).
Time varies based on country of origin. Each country is allocated a fixed number of spots, and these spots of of similar size for all countries. So, if you're coming from a small country (i.e. Iceland) it's easy. Coming from India/Mexico, then you'll have to wait a while..