Machine already loaded with PC3200, add same or higher OK?

Hi folks, I've been lurking for a week or so trying to gain knowledge which has been fruitful but didn't quite answer my question. I have a Dell 4700 P4-2.8, running 512 MB of what appears to be PC2-3200 DDR. On the memory itself the following is stamped "1RX8 PC2 3200 U 333-10". I am assuming this is 333MHZ memory. In my shopping for a couple of gigs of memory it appears the 333MHZ stuff is hard to get. 533 MHZ memory is plentiful and from reading here it looks like I can run it, it just won't run at 533 if my motherboard doesn't support it. I don't know which motherboard I have, took the cover off but couldn't see, label is probably on the other side. Am I OK running slightly higher speed memory or should I look harder for 333MHZ RAM? Have I identified my memory correctly?
Thank-you for any responses.
Chuck

That actually looks like the rare DDR2 3200 memory. I don't think that 333 in the part number indicates speed. And, faster memory "might" work but it will depend on your MOBO+ bios' ability to run the memory at a slower speed. I would suggest you check with Dell and/or the memory maker of your choice to be sure.