Here is a little PC 101. So have a rough price in mind you want to spend, keeping in mind that basic parts are need for a pc build. Think what you would like to use your pc tower for (leisure, gaming, business). So here are your basic parts.
1. PC Tower
2.Power Supply (sometimes integrated with the tower when bought).
3.Motherboard (where your ram, cpu, videocard, etc go). (video card can be intergrated on board for cheaper designs and builds).
4.CPU (this would be your microprocessor). (currently available up to 6 cores).
5.Ram (otherwise known as memory).
6.Keyboard and Mouse
7.CD/DVD/ Blu-Ray Drive (a basic cd/dvd reader all the way up to burning your own blu-ray or dvd).
8.Monitor (if needed).
9.Hard Drive (where all the information on the pc in stored).
10.Software (microsoft windows 7)
Extras
11.video card (makes your graphics better for viewing/gaming).
12. audio/add on cards (wireless internet card, firewire adapters, usb adapters, etc.)
13.extra cooling fans
14.water cooling instead of using the oem supplied cpu fan.
15. media panel (can be used to add extra sata,usb, card readers for camera/camcorder memory cards. Also fan speed and case temps can be monitored as well with the better models.)
16. Interior case paints/cathodes/lights and other random customizations.
17. web cams (great for skyping!)
18. headsets (used for more private listening or one with a mic for gaming and chatting!)
19. Scanners and Printers
20. speakers (from cheap as you want to 7.1 surround sound...your choice!). Some are included if not built in to monitors
I enjoy building P/C's so let me build one for you, Your Way!