Sorry for the delay Whiskas,my timer beeped on the microwave as I was about to answer and I thought Adept would have sorted you out
When you got your motherboard and CPU ugraded did the guy give you a cd with the drivers on for the display and sound etc?If he did do the following,if not get back to me or go into Pals chatroom and we can go through it there maybe easier.
Go to Control Panel,Display,click on Settings(Far right Tab at top),Adapter then click on change.Put your Cd in the drive and click next,make sure its marked search for better drivers then next,then tick the box next to cd rom and click next.
All being well it should find them off the CD and install them.It wil probably want to reboot so do that then see if you can set the resolution and colours to what you had before,probably 800 x 600 and 16 bit colours.