Where can I find this for cheap? I looked at tigerdirect, they have a stick of 512 for $224.99

I might just buy 2 sticks of 256 or save up for two sticks of 512. Who knows.

My motherboard has for slots, each can hold a minimum of 128MB and a maximum of 512MB.

I might just end up buying a new motherboard, but that all depends on how well my new GeForce 5900XT will work on AGP4X. I know it will be limited to how hard the card will work, but how much of a difference is AGP4X than AGP8X?