Please check the parts for my new system

I will be upgrading my computer and i would appreciate it if you would look over the parts to see if they would work together fine. Im a bit concerned about the motherboard as its using the old g31 chipset. It only supports up to ddr2 800mhz and only has one pciex16 port. Would the non 2.0x pcie port still support one 4850 card fine? I have no interests in crossfiring in the future and i dont need more than 2 memory slots.

here is the list of the parts on newegg. I will not be using newegg to purchase this tho.

mobo-Newegg.com - GIGABYTE GA-G31M-S2L LGA 775 Intel G31 Micro ATX Intel Motherboard - Intel Motherboards
case+psu-http://www.newegg.com/Product/Produc...33&Tpk=NSK6580
hdd-Newegg.com - Western Digital Caviar SE16 WD6400AAKS 640GB 7200 RPM 16MB Cache SATA 3.0Gb/s Hard Drive - Internal Hard Drives
cpu-Newegg.com - Intel Core 2 Duo E8400 Wolfdale 3.0GHz 6MB L2 Cache LGA 775 65W Dual-Core Processor - Processors - Desktops
mouse-Newegg.com - Logitech MX518 2-Tone 8 Buttons 1 x Wheel USB + PS/2 Wired Optical 1800 dpi Gaming-Grade Mouse - Mouse
gpu-Newegg.com - MSI R4850-T2D512 Radeon HD 4850 512MB 256-bit GDDR3 PCI Express 2.0 x16 HDCP Ready CrossFire Supported Video Card - Desktop Graphics / Video Cards
Ram-http://www.newegg.com/Product/Product.aspx?Item=N82E16820231171

$102 GSkill G.Skill PI F2-6400CL5D-4GBPI 4-4-4-12 4GB Kit (2GB X 2) DDR2 800 PC6400 Heatspreader RETAIL PACKING RAM
$83 Gigabyte GA-G31M-S2L S775 All-In-One Motherboard
$128 Antec NSK6580 NSK-6580 NSK 6580 Tower Case With PSU
$94 Western Digital W.D. WD 640GB SATA II Serial ATA100 HDD 7200rpm Hard Disk
$258 Intel Core 2 Duo C2D E8400 3.00GHz (LGA775) CPU Genuine Retail Box
$209 512MB ATI 4850 Generic-MSI HDMI DVI PCI-Express PCI-E Video Card
$29 Logitech Retail MX518 Gaming Mouse
Well these are the prices from my Aus retailer

Im planning on using this computer for moderate amounts of gaming. I would prefer it to run quiet and i wont mind in investing in a new cpu cooler and extra case coolers if it would help towards that purpose(i intend to regulary leave my computer on overnight in my room as i sleep). I heard that my case+psu is reasonably quiet and functional, does anyone know much about it?

Would the dd2 800 ram bottleneck my fsb? esp with overclocks on the cpu. Theoretically ddr2 800 can support a 1600mhz FSB(at least from what i read) through the formula 800/2X4 (or just 800x2). by default the e8400 runs at 1333mhz.

I know that pciex16 and 2.0 are compatible with each other but is there any performance loss? Like if u put an old pcie8xgpu on a pcie4x slot the speed would be reduced to the maximum bandwith of the lane(if memory serves me right). I dont know if that is the case with pcie 2.0 cards and the pciex16 lanes.

If this motherboard can run my system without any serious drops in performance then i would be saving myself about $100AU by not buying one with a p45 chipset. But i will buy one if its necessary to maintain the performance of the cpu + gpu. I may try to do some overclocking to the cpu if the stock fan and motherboard supports it, but it wont base my decision on overclocking. I would appreciate any recommendations to the system as long as it remains relatively close to the current costs(well if there is a significant improvement to performance or decrease to noise i wont mind)