Memory

I have a Intel D865PERL Motherboard with 512MB DDR333/PC2700 DIMMS. Can you add a DIMM module of 512MB DDR400/PC3200.

Yes you can, your mobo has the ability to hold up to 4Gb DDR400 SDRAM modules :

http://www.intel.com/products/motherboa ... /index.htm

If you are looking to install extra RAM, just keep the same speeds as any RAM you do install, if it is faster than the current RAM speed, it will have to underclock. I.E. PC3200 mixed with PC2700 will run at P2700 speeds, NOT PC3200 speeds.

A better option would be to remove the old DIMM completely.

it is also a more expensive option

The cheapest option isn't always the best option though.

tru dat