Is DDR2 6400 compatible with 6400U?

[AffanTech]

I have 4 GB installed on my 4 year old dell xps 420. I plan to build a new computer in a few months but till then i am in need of a memory upgrade as my win7 64 bit OS is running mac os x and linux mint on vmware workstation and its a memory hog! I am thinking of upgrading to 6GB. I went to crucial site and compatibility check showed i should get 2 GB 240-pin DIMM, DDR2 PC2-6400. So in my search for a good deal online i found someone selling a 4GB Kit (2GB x 2) DDR2 PC2-6400U 800mhz 240-Pin DIMM Desktop NEW OEM. The only difference i see is 6400U instead of 6400. I couldn't find anything on the difference when i researched online. Will it still be compatible with my machine? Thanks!

 

[AffanTech]

Apparently U stands for unbuffered so i think it should be good, fingers crossed!