OK, if you're not overly serious, and you're just starting out, then there are a few options that may fit, but I would recommend getting the memory yourself, because most companies overcharge for the memory.
OK so this would be sort of a baseline for a nice Corei7 (which are a little new to give great options a little low on the graphics side, but fits everything else;
http://www.shopping.hp.com/webapp/ [...] tqe_series
Has an OK CPU, and and a medium-ok graphics card with a high res screen.
Better Graphics card;
http://www.newegg.com/Product/Prod [...] 6834115679
but you could get better with a Core2Quad, it's just a little hard looking for them.
I'd recommend looking at a Gateway or MSI for good options, but I can't seem to bring them up on the US sites for the models I like so not sure about US pricing.
For MSI Global, this would be my recommendation;
Core2Quads;
http://www.msi.com/index.php?func= [...] od_no=1794
http://www.msi.com/index.php?func= [...] od_no=1676
And depending on pricing, a core i7 solution;
http://www.msi.com/index.php?func= [...] od_no=1902
That should give you an idea, but it's a little harder than it used to be to find pricing.