I've been using the Transcend 120x and 133x 8Gb CF cards for quite some time now with no problems. It's been about 3 years already.
I'm currently using the 300x UDMA 8Gb cards. Also no problems. But you ought to read the thread here where a CSer had problems with this brand. I'm using a Nikon system and I've not had any problems with Transcend.
Use Transcend 133X 8GB and 4GB for almost a year with Nikon so far no problem, quite reliable, filled up the 8GB card on a few shoots and no issues at all. Saw they got faster speed cards but price/performance wise, 133X is still best value for money.