mixing memory

[cfrage]

I have an Epox 9NPA+ Ultra and currently have 2x512 PC3200 Samsung ram. I can't seem to find my ram anywhere or I'd buy the exact match... Would it be ok to stick two 512 sticks of the same speed but of a diff brand in my open banks? Played FEAR on my new system and with 1GB it was having to write to VM. On my old system the gfx were not nearly as good, but it ran smoother due to the 1.5GB.