memory upgrade advice

I've just added two identical sticks of 256mb ram in my wife's gaming machine (4x256=1gb) so my brother was pleased at the improvement in performance,so now he would like to add these http://www.newegg.com/Product/Product.aspx?Item=N82E16820211013&Tpk=N82E16820211013 in each slot(2 of the 4) alongside of what he has now in his game machine http://www.pcplanetsystems.com/abc/product_details.php?category_id=107&item_id=493 , the question is will they work together ? that would make his gaming machine 1.5 GB ram,I never mixed different sticks before, so i just want to be sure.

thanx,
pistol

 

Crucial.com is the only place I get my memory from.

 

it's not recommended to mix ram types/sizes. maybe some more info on the motherboard would help. model, etc.

 

this is the model of the mobo used in the system running Xp pro
http://www.msi.com/product/mb/865PE Neo2-P Platinum Edition.html#/?div=Detail

 

i informed my brother that mixing sticks of different sizes can be risky,so he relented, and i suggested he purchase these instead since the specs match very closely to what he had been using,his aftermarket mobo also should auto detect them too hopefully without going into the bios to make any of the necessary changes if needed.
http://www.newegg.com/Product/Product.aspx?Item=N82E16820231032

 

as long as the fsb is running at 800mhz, ddr400 will work fine. You still may want to make sure that it's running optimally once installed. should display that it's running dual channel during boot.

 

thanks,will do
he just ordered them this morning ,so when they arrive he'll drop off his machine and sticks at my place for the installations,I'll be sure to let you know how it goes.

thanks again

 

new memory modules installed,instantly recognized by the machine,a little confused on setting up page file size..so i chose the "let windows option",
noticeable immediate positive impact on speed and overall performance.
fsb auto set itself to 800mhz,everything went smooth,all i basically did was to just install them and that was it,the MSI motherboard did all the needed adjustments.

thanks Smoke,

pistol