Here you go ..
Which are compatible to Q8300, support 8 GB DDR3 RAM ..
You can compare these board features from below link.
Of the 4 boards suggested which one is the closest to original?
Where can I buy any of these from and how much are they?
Will they all fit in my Dell tower with the correct proprietary parts, cables, connections already there?
To purchase the same please visit .. below link..
For price details you can conatct any resellers in your city ..
Your cabinet shoudl match this product, however you can check the mothebroard form factor and cabinet form factor before purchasing the same.
Cabinet should be ATX form factor.. Motherboards support ATX form factor..