Case: Antec Mini P180
PSU: Power Supply CoolerMaster 550W
MOB: Gigabyte GA-EP45T-UD3LR P45+ICH10 FSB1600 DDR3 SATA2 GbN RAID
CPU: Intel ATX E8400 CORE 2 DUO /3.0GHz/6MB/1333FSB/LGA775
GPU: Sapphire HD4870 512M
RAM: GSkill 4G(2x2G) DDR3 1333 PC10666
DRIVE: Pioneer DVR-216BK 20x Dual Black
HDD: WD 500G
Are all these compatible ? Do i need a better quility or more Watt PSU ?
No, this is a rather low wattage system (other than the HD 4870.) It would be fine with a 250W PS. I have a crappy Cooler Master PS, and I wouldn't recommend them as a brand, but it would probably work fine.
500W-ish is a good spot to be if you never want the PSU fan to ramp up to audible (assuming a decent PSU to start with).
Bad advice. I keep seeing this myth repeated. Wattage rating has nothing to do with PS fan controllers. My cheap 300W In Wins ramp slower than my 430W Cooler Master. The PS fan has to cool the waste heat of the PS, which has to do with efficiency and load--not maximum load rating. Don't expect a crappy 550W PS to be any better than a crappy 250W PS as noise--if anything the higher wattage model will be worse.
The motherboard is probably okay, but doesn't really offer anything over what much cheaper motherboards can provide. Doesn't the Mini P180 only accept micro ATX motherboards?
The WD 500GB seems like a poor choice. Step up to a WD6400AAKS.
The E8400 is good, but if you plan to overclock it won't be a whole lot faster than the E5200. The E5200 can be difficult to overclock though. The E7x00 series are a nice compromise.
There's no real advantage to DDR3 over DDR2. Get whichever is cheapest. Core 2 Duos can't even use DDR2 800 effectively due to the slow FSB. Major FSB overclocking is needed to make any use of any faster memory.