It's overkill, even at 1600x1200x32bpp there are only a handful of games that see any gain with 64MB of RAM rather then 32MB of RAM.
Unless your running at 1600x1200x32bpp w/ 2X FSAA I sincerely doubt you will ever see any benefit, and in most cases you won't see any gains until 4X FSAA at 1600x1200x32bpp.
Many games only use approximately 28.12MB of RAM when rendering at 1600x1200x32bpp, and less then 16MB of RAM when rendering at 1024x768x32bpp.
According to the developers of Max Payne which is one of the most graphically intensive games currently available reportedly only uses on average 9.4MB of RAM when rendering with maximum detail settings at 1024x768x32pp, with 4X FSAA this figure jumps up to an average of 37.6MB of RAM, with peaks of about 44MB.
Basically, if your playing in 1600x1200x32bpp w/2X FSAA then I can see you benefiting slightly. In 4X FSAA you should see definitive performance benefits.
FWIW, the nature demo of 3DMark 2001 actually consumes 40MB of RAM in default setting though. Mind you that's still over double what any real world games utilize at 1024x768x32bpp... but it does go to show that a few years down the road we could be using massive amounts of RAM compared to what is typically seen today.