HELP computer wont start..

Hey guys i finsihed my computer and i had a probem with it b4 so i sent it to candas computer to fix it and they did.. so nothing wrong with it they just fixed a few things and intsalled it. the probem is i dunno how to install windows xp. what should i do first? install my motherboards cd? or put windows xp rightaway? im really confued becuase i started using the bios and it all all good. when i first turned on my comptuer i notice the fan for the cpu is lound.. but i had no problems because the cpu temp was i think under 20 but now after i keep turning it on and off figuring out how to start the dam comp my fan went from 2700 rpm to 300-400 and no the cpu wnt up to 30+ im scared to keep fixing hte menus nad settings but i cant get it started.. anyone PLZ before i **** this comp up tell me waht should ido.. what setings i should make. heres my sepcs and im using my old comp right now.

Case - Coolermaster Centurion 5
HDD - Seagate 250 GB
DVD Drive - Im using 1 right now i hear u need 2 but its a LG RW SATA one.
RAM - 2GB Corsair
Motherboard - Gigabyte P35-DS3R
PSU - Mushkin 550 Watts
Videocard - EVGA Geforce 8800 GTS SuperClocked
CPU - Intel E6600
CPU Fan - Thermal take brand

i think thats all... anyways with all the things is aid... what should i do now? i want to install windows and make it work like my computer not but not as slow lol.. anyways yea what setting should i do? right now everytime i turn my comp the fan is slow for the cpu and the first time i turned it on it was loud at 2700 RPM so there is a problem here. anyways any help plz?

30c idle is not too hot for that CPU. Put the XP CD in and boot. If it doesn't read the CD go into BIOS and set the boot order for the CD to boot first and save. After loading XP put the MB driver CD in and load the drivers. Based on your post your knowledge is limited, so don't make too many changes to the BIOS or you will screw it up. If, and only if, it does get screwed up, reset the BIOS CMOS according to the manual. Do it exactly as stated in the manual. Only as a last resort because the shop may have made changes to the default BIOS setting and you don't want to lose them.