Hardware and OS help please (gamer type system build)

I am getting ready to build out my system with the following components, but don't know about two things. I kinda went over my $650 range I wanted to stay in, but felt that the parts I put together should be pretty game proof for at least a couple of years, and I plan to overclock the CPU. I mostly play games on my 5-6 yr old Shuttle PC and it is now extremely long in the tooth when running the absolute lowest settings in my games from the Steam and EA store. But after pulling down the latest Prince of Persia and it being a choppy slow mess with these crazy lines that extend from the characters (what the heck causes that?), i finally said enough is enough.

Anyway, my questions are:
1. Do you think the vid card I selected will work with the other parts? I play mostly FPS-type games, Strategy and MAME
2. What OS to go with? I am still a little gun shy on getting and running Vista and don't know what/why I should go with 64-bit over 32-bit

Specs I was intending to get:

Intel Core 2 Duo E8400 Wolfdale 3.0GHz LGA 775 65W Dual-Core Processor Model BX80570E8400 - Retail
Foxconn BlackOps X48 LGA 775 Intel X48 ATX Intel Motherboard - Retail
--- Combo price of $334

G.SKILL PI Black 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model F2-6400CL4D-4GBPI-B - Retail

G.SKILL FM-25S2S-64GB 2.5" 64GB SATA II Internal Solid state disk (SSD) - Retail

MSI N9800GT 512OC GeForce 9800 GT 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready SLI Supported Video Card - Retail

Rosewill TU-155 II 500 Black 0.8mm cold rolled steel ATX Mid Tower Computer Case 500W Power Supply - Retail

OCZ OCZ700MXSP 700W ATX12V V2.2 / EPS12V SLI Certified CrossFire Certified Modular Active PFC Power Supply - Retail

LITE-ON 20X DVD±R DVD Burner with LightScribe Black SATA Model iHAS220-06 - OEM
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All said and done; $878 before rebates

Additional Notes:
I have a 24" Dell for my monitor and 2 1TB SATA II disks that are no longer used from my Mac Pro. So the SSD will only be used for the OS and the 2 other drives for normal data.

Thanks for any help you can give me!