Mount Umbrella

Whats a good photography flash kit and how much should I realistically expect to pay?
Doing portraits indoors, not a huge space but maybe some day.
Already have a continuous lighting set up (only 2 lights) but I want the convienence of flash. Should I just buy some flash heads and mount onto my stands and umbrellas or just buy whole kit.
Using Canon XTi/400D.
I am considering this light kit. http://www.backdropsource.com/Productinfo.asp?id=3075&pname=320-watt-flash-light-kit-with-two-umbrellas Will that be strong enough?
Please don’t take offense but – if you haven’t checked out a few books on studio lighting then that would be a good place to start. Another good source of information is shutterbug.com – just type in studio lighting and see what comes up. By doing this research you’ll learn what working pros are using and then you can make informed decisions. Having a complete stranger tell you what to buy is of dubious help. The set-up they swear by might be more – or less – than you need.