Bits and Bytes:
The 8 bits to one byte is very important as has been mentioned, so make sure you get this right. Capital B generally means bytes, whereas lowercase b is bits, but this is not always the case. So really, you just need to ask the ISP if you are talking bits or bytes. From my experience, bandwidth from ISPs is almost always bits.
Google Can Do It!:
If you want to be nice and lazy, just Google the following:
10 megabytes in kilobytes
10 megabytes = 10 240 kilobytes
because Google calculator will do this for you, you can change bytes to bits in either or both to suit your needs. :-)
There is upload speed and download speed, half-duplex and full-duplex, and also very important in choosing an ISP is latency. I recommend you go and research these topics a little bit and grill the ISP tech-sales person about them. If they are good sales people, you can also just say "I heard latency is important, what is the deal with that?". But the more you know, the better you can tell if you are getting quality honest answers.