Word to the web wise... research your reseller as many resellers resell themselves and you find domain name companies, especially those in the US will try and cut your bread and butter out by contacting YOUR client directly behind your back as has happened several times to me as an end user.
Your entering a cut throat world of backstabbing and cheap tricks to do you out of your money by making you really work for it. I did a cursory search for web host reselling and got more than 25 Million hits.
Not wanting to **** on your bonfire but I think you need to diversify a bit more than just reselling. You may want to consider a more Niche market and act as a broker to business clients who you can charge for your time and efforts and a fee for setting up the hosting plan.
I will admit that 8 years ago I had the brainwave of jumping on the reselling wagon only to find that it was an already rammed gravy train that has been well engineered and greased to that the only winner at the end of the day is the hosting company who get the lions share for our hard work. Grrrrrrrrrrrrrrrrrrr
The only way that you will make money in reselling rackspace is to actually become a rackspace supplier and have minions running around reselling your product for you whilst you play golf on a nice links course.