Hello, i have an ASUS P5VDC-MX (socket 775) Motherboard, and it has 2 slots for DDR memories and 2 slots for DDR2 memories, the manual says that i should not use DDR and DDR2 memories simultaneously, but i want to know if there is a real risk on doing this? does anyone uses DDR and DDR2 memories simultaneously? I have now two 512 DDR´s, and want to put an additional 1 GB DDR2. Thanks a lot!!! Pentium D 3.4 Ghz. 1 GB RAM 2x512 DDR. 80 GB IDE HD. ATI Radeon X1300 512 MB. Ralphmex.