What are different connection speed ratings

ISPs typically advertise in MegaBITS per second, you're measuring in KiloBYTES per second. And then, you never get everything you're paying for, so 100kB/s on a 1Mb line seems about right to me, unfortunately!

Example: I have an 8 megabit/s line, meaning I should get 1 megabyte/s. I get close, sometimes, but most of the time I get about 2-300kb/s.

For Remote Desktop, you can pretty much get away with Modem speeds; anything faster will just make your user experience that much more plesent. The real kicker is going to be latency, how long does it take for a packet to travel from your connection in India back to your home office. Anything longer than 500ms will introduce noticable lag in a Remote Desktop session, latency above 2000ms will be almost unusable (though high level of patients will help).

That said, any wired connection of moderate speed (512kbps should be fine) will be more than sufficient for Remote Desktop.

If you intend to stream any music or video (for fun or work) you may want to go up to a higher speed, but like I said, it all depends on what you want to do.