Hello everyone! I've been researching over the last week or so and I think i've finally got a spec for my "First Build" hopefully it won't melt and or blow up!

Config:
E4300 + Arctic Cooling Freezer Pro 7.
ASUS P5B-E PLUS.
2GB Corsair TWIN2X 6400 DDR2, Two/Paired CM2X1024A-6400 Dimm's.
Sapphire Radeon X1950Pro 256MB GDDR3.
Seagate Barracuda 320GB 16MB Cache@7200.10RPM.
NEC DVD-R AD-5170 IDE Black OEM DVD+R/+RW/DVD-R/-RW (Dual layer).
Sony FDD 3,5" 1,44MB Black.
Thermaltake Armor Jr Black W/side window. (Bought Already).
Cooler Master iGreen Power 500W PSU. (Bought Already).

Samsung 17" LCD Syncmaster 740BF TCO-03 Silver, 1280x1024, 700:1, DVI-D, 2ms.

Windows XP Pro 32Bit OEM

Accessories:
Saitek Eclipse II Keyboard.
Logitech MX518 (Bought Already)
Logitech Precision Gaming Headset.
Steelpad QcK Professional Cloth Mousepad.
Creative Inspire T3100, 2.1 Högtalar- system, 2X6W + 17W sub, Retail

I just have a few questions for you:
#1 - Is this a good Over-clocking/Gaming Spec?
#2 - What estimated clock speeds could I reach with this build?
#3 - Would you change anything?
#4 - Would you choose XP Pro over Vista Home Premium?
#5 - If anyone has a similar build what benchmarks are you getting? And are they impressive? i.e. PCMark / 3DMark etc...
#6 - Would I need a sound card for the speakers above?

All comments are very much appreciated I never fully understood just how much time and effort it took to find a good spec'd Gaming build so i'd just like to thank everyone that has been kind enough to reply to my threads and help me on my way to my first build this will also be my first overclock so I hope you nice folks can help me out as always!