I see 512mb stick of memory on TigerDirect for 39.99! they are PC 3200 400mhz Ultra Memory. They are CAS3... My current memory is 2*512's of 3200 400mhz CAS2.5 Corsair... Will they work together? (the two corsairs will be dual channel with eachother and same for the Ultra) or will i get some errors?