Right, so, currently MTNL and MTS have decent wireless broadband plans.
MTNL is GSM 3G. MTS is CDMA EVDO RevB.
If you have decent MTNL coverage, expect around 2.5-2.8mbps.
http://mtnldelhi.in/dolphin/index.php/mobile/3g-services/3g-tariff
The unlimited plan costs 1600 bucks, both prepaid and post paid.
EvDo is the 3G equivalent of CDMA, if might say.
If MTS coverage is good, expect around 4mbit (very subjective)
http://www.mtsindia.in/Delhi/MBlazeUltra_postpaid.html
40GB for 1000 bucks, postpaid. If you go prepaid, you'll only get 20GB
Now, pings will be terrible on either, so, don't consider gaming on these connections.
MTNL, being GSM, get a prepaid sim, test the speed using your phone, if you like what you see, buy a dongle and et al.
MTS, request for a demo, if you like what you see, buy their dongle. With mts, you'll be tied to their dongle (not sure if their newer dongles can be unlocked), with mtnl, you can buy an regular 3G/HSPA dongle from
flipkart or whatever, and use any GSM sim card.