do I need faster memory?

[ianm2]

I am also getting some more memory, 4gb, I have 2bg cruicial 533, and it works well, using a 4400 cpu, to be updated later.

however, prices are excellent now, so should I get some 667 or 800 speed.

options are

crucial ballistix 800 cl4
corsair xms2 667 cl4, absolute bargain now.
ocz platinum cl4

I don't overclock, so do I need the headroom?

[Adamantine]

Ram speed, timings, etc. is almost irrelevant for a non OC'er. If you move up to 4GB, by the time you're ready to do a big overhaul upgrade, you'll probably be upgrading to DDR3.

[LC_STiK]

if you're not OCing, get the cheapest RAM you can that has decent timings.

But I'll tell you something, OC'ing is loads of fun.

[Yellowbeard]

Ideally, you don't really want to mix and match memory on a dual channel MOBO, and especially AMD as the memory controllers can be sensitive to latency or IC differences. I'd suggest that you either exactly match your existing memory or, buy 4gb of matching memory. Also, on an AMD platform I'd suggest a 2 x 2gb kit as opposed to 4 x 1gb.