Mixing Brands of RAM

I am currently using Crucial PC 2700 DDR333. My problem is that 3 out of 4 256MB memory stick from them have been defective. I am operating on the one good stick they have sent me. I have sent two of the four bad ones back and have one bad one sitting on my desk now. But I refuse to pay postage again to return another bad memory. So I am just going to eat this last bad memory stick and would like to add to my computer another 512MB of memory from another manufacturer. My Questions is: is it allright to mix brands of memory as long as I use the same type in relation to speed. ie; PC2700, DDR333? (And the CAS2.5.)
Has anyone had problems mixing brands?

I'm surprised you had such trouble with Crucial, they are a good company. FWIW, there are only a few actual manufacturers of RAM, so if you get another brand, it may very well be the exact same thing with a different label.
I also think that eating $30 or however much the RAM was to avoid $5 postage is not such a good plan.
Anyway, you should be ok mixing brands as long as you match the specs. I've heard of occasional hanging problems and such, but not often. (Then again, you do seem to have bad luck...)
Still, I think you'll be ok.