Need help!

First off I know this is the wrong board and I apologize but I got to leave in an hour or so and will be gone for a few days and so I need to order today if possible and don't have the time to wait on the ram board to answer.

Which Ram should I choose

Should I buy one(1) stick of
Kingston HyperX Series 184 Pin 512MB DDR PC-2700
(limit 10 per customer)

- Specifications -

Manufacturer: Kingston
Speed: DDR333(PC2700)
Type: 184 Pin DDR SDRAM
Error Checking: Non-ECC
Registered/Unbuffered: Unbuffered
Cas Latency: 2-2-2-5-1T
Support Voltage: 2.6V
Bandwidth: 2.7GB/s
Organization: 64M x 64 -Bit
Warranty: Lifetime

and run it in dual channel mode with my current stick of the same ram or buy two(2) of these

Kingston 184 Pin 512MB DDR PC-3200 - Retail


Model# KVR400X64C3A/512
Item # N82E16820141424
Specifications:
Manufacturer: Kingston
Speed: DDR400(PC3200)
Type: 184 Pin DDR SDRAM
Error Checking: Non-ECC
Registered/Unbuffered: Unbuffered
Cas Latency: 3-3-3
Support Voltage: 2.6V
Bandwidth: 3.2GB/s
Organization: 64M x 64 -Bit
Warranty: Lifetime

and run these in dual channel mode and put my stick of hyper x in its own slot.

What Cleeve said. I concur.

If i put the 3200 in the dual channel with the 2700 hyperx i already have will the 3200 automatically underclock itself? Also i have the asus a7n8x deluxe mobo and i read on another post that i could run them in dual channel dispite their speeds because it runs the ram on individual (pipes?) rather than a single one at 128 or something like that.

(man having an unmonitored computer at work is great)