OWC mac memory?

Anyone use OWC's/MacSales.com's memory? I believe there's two types offered: OWC Mac Pro Certified (slightly higher $), and OWC Apple Qualified (slightly lower$). Any probs? I'm just getting 2GB to supplement my current 2GB (Apple OEM 4 x 512). Oh, BTW, two 1 GB sticks will work with the four 512s, right? Do I just leave the 512s where they are and then the two 1 BGs go after? Or should the 1 GBs lead? Thanks.

I'm currently using this OWC memory in my MacBook-- it works beautifully.

I like working with OWC-- good people, good products, good service. I like newegg just a bit more because of their wider product line.

I have Crucial memory. Works fine. I have 2x512 in the second memory board and 2x1GB in the first board.