Memory check if its compatible for my mobo

[Condor]

Hi

I'm new to memory upgrade, could anyone help me to check if the new ram is compatible with the old one because I'm putting 2 more gigs next to the old ram to make it 3 gigs.

CORSAIR
http://www.newegg.com/Product/Product.aspx?Item=N82E16820145440

G.SKILL Value
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231036

Mobo I'm currently using
http://www.newegg.com/Product/Product.aspx?Item=N82E16813138264

side note: The reason why i got an extra G.skill ram is because the new Corsair i brought in to Bestbuy the other day for installation was bad? , the tech told me my PC won't start up when he put the the similar stick of Corsair ram to the existence one, so i went out and purchase the G.skill instead from newegg and hopefully its compatible with the old one.

So my other question is, was the secondary Corsair a DOA or can the Bestbuy tech fix it by adjusting my PC bio or other setting?

thanks

 

[raybay]

it usually works, but it is NEVER good to mix memory modules... all working well individually. You will always note a hit in performance, and some will make the computer noticeably slower.
Better to sell the old, and install all identical modules...

 

[Condor]

thx for the rely

question: any recommendation on how much should i sell my old ram on the auction house, like Ebay? : D

thanks

side note: is the new ram (G.Skill) reliable? because the old one i been using it for almost 3 years now.
Hopefully the new ram won't give me much trouble, because I use my PC mostly for hw, web searching and lots of MMO gaming