DDR 500 is DDR1 not DDR2. AMD CPUs will start supporting DDR2 once the Socket AM2 CPUs are released, up until then Athlons and Opterons will only support DDR1. This isn't neccessarily a bad thing, DDR2 isn't always better than DDR1 - memory timings and latencies are still relatively poor on DDR2, the performance advantage is in the available bandwidth. RAID 1 on a desktop system is too expensive, it's a much better option to just perform backups every couple of weeks (or whenever you create something new that you want to protect). Write performance on RAID 1 is worse than a single disk. The risk you run is that you have a silent failure - how do you know if you have a faulty disk ? Some of the cheaper RAID controllers just carry on regardless using the remaining mirror and you don't know you have a problem until the second disk has a fault... need to be careful with that. Also, Opteron 1xx CPUs (Denmark core) are effectively the same as Athlon64s with the Toledo core. The only real difference is the fabrication process and quality controls AMD put in place since the Opterons are server/workstation chips which require more rigorous testing and generally run at lower core voltage/produce less heat. This makes them potentially better for overclocking as they should be higher quality - but if you aren't planning on OCing the CPU it's hard to justify the increased cost.