You will notice the difference. Newegg has some gskill ripjaws for about $80 after rebate last time I checked. I've had no problems with the 1600 version.
Thanks for the reply, but they aren't such a good price here in the UK.
I've seen it mentioned that it might be better to buy 1600's to run at 1333, instead of 1333's. But knowing my luck it wouldn't work out that way for me.