Will 3GB (2x512 DDR400 & 2x1GB DDR333) out preform 2GB (4x512 DDR400)?

My current PC has the folowing memory paired with Athlon 64 X2 3800, Asus A8N-SLI Pre, a Asus 7800GT gfx card (Dual 20" Widescreens), running Vista Ultimate 32-Bit:


1GB (2x512MB) of Corsair’s XMS TWINX1024-3200C2PT (DDR400) with Cas Latency 2 and Timings of 2-3-3-6
and
1GB (2x512MB) of Corsairs's XMS CMX512-3200XL (DDR333) with Cas Latency 2 and Timings of 2-2-2-5


Would I see any advantage from replacing one of the two paris above with:


2GB (2x1GB) of pqi POWER Series MD342GUOE-X2(DDR333) with Cas Lalency 2? I don't know the timings.


This may be a dumb question but I have been out of the loop on this type of stuff for a while. I'm not really looking for gaming performence. I'm looking to give Vista a little more to work with. I mostly run Office 2007, iTunes, Picasa 3, Google Earth, Sling Box Solo, Rips DVDs and rencode them for my iphone, Web Browsing with at least 10 windows or tabs open, and Seagates auto backup software running in real time. I don't have any major performence issues now but figured it might be worth adding the extra.

I hope to stick with this PC until Windows 7 SP1 comes out.