Hi Lisa
If you have a look at
this article on Buying an Embroidery Machine it should assist you in making your purchase.
I'm not a machine embroiderer myself, but it's mostly those at the top end of the market that do quilting and machine embroidery. Most good embroidery machines can also be used for plain stitching, and all of them utilise digitised patterns - however they all have their own formats, which you have to be careful of when you download anything from the internet.
A warning about downloading - like any download it can be dangerous. Unscrupulous people include spyware and viruses in these patterns like they do elseware. DOwnload only from a reputable source - usually the manufacturer's website is safest.
You also need to ensure that your computer is compatable with the transference method into the machine. It's no use downloading, if you can't get them to your machine.
I hope the article helps - and I know that there are a couple of machine enthusiasts here that will, no doubt, help more.