Well its more along the lines of what type of Ram memory should you buy
I wold say DDR PC3200 400Mhz, wold work but i wold recommend DDR PC2700 333Mhz most electronic stores might have some but i fell they are getting hard to find., On the how much will it support. . . most websited will say 1 GB, ive fixed similar models and they top out at 2 gb some almost 3 but just me testing.
i wold say as much as the Operating System wold let you to use, dont go nuts and go for 2GB