In reply to streapadair:
If you upgrade the mobo you'll have to upgrade the processor as well (and you'll have to make sure the cpu you buy fits the mobo you buy!). Probably quicker to just buy a new machine if you're not going to build it yourself, though really anyone can with any of the hundreds of walk through vids on youtube.
Would suggest if you do get a new machine you get it custom made from a small store, it'll work out cheaper than buying a branded machine.