As you can see, there are tons of you tube video how to’s, and you can google any question about xbmc and get an answer.
For instance I just googled “how to insall XBMC” and this was at the top of the list of returns...
http://wiki.xbmc.org/?title=XBMC_Quick_Start_Guide
All you need is 6Mbs internet download speed to use XBMC.
DSL or better should work fine, but faster is always better.
got 20mb via dish as we speak