Britek has been around for some time as a producer of lighting equipment for flah photography - they made a fortune off the lil' gadget that works as a slave for photoflash units.
The quartz units have been around for a few years. They are not overly rugged, meaning I'd never suggest their use in a hardcore shooting envrionment - say, daily news. These light compare more to Smith-Victor and early Colortran units than current Mole and Arri fixtures. With proper care they should last a few years, certainly enough to recoup your investment.
Ushio is a lamp mfg. and they make a wide range of globes. I have bought 100w through 1000w lamps made by them and they've performed as well as lamps by GE, Sylvania/Osram, etc. In fact, I recieved Ushio lamps with my last Arri kit purchase - they are still operating with no discernable discoloration or fade.
As always, you get what you pay for...you may find that you don't have the range of accessories that work with Mole, Arri and other brand names, and they may not be as rugged or useful in all situations.