OT: Hardware Question

[btaft]

I am considering fairly major hardware upgrade and have a few questions I was hoping to get some feedback on:

1) Does a RAID 1 Array adversely affect game performance. I am considering this for data protection.

2) If I have dual DVI outputs on a card and dual monitors can I send the same picture to both without taking a performance hit (I.e. the same data just getting sent to two places)

3) If a motherboard has two PCI Express slots and is listed as crossfire capable does this mean that SLI is not supported or is this purely between the cards and the operating system.

Any help is appreciated.

Thanks,

BT