SOS: Both Computers Dying, Need Advice On Replacement

Story is my main desktop is just getting old and stupid and the laptop is a pretty beat up little thing that wasn’t all that good to begin with and now has a stubborn bit of spyware on it. I can live with the laptop for now, but my desktop is in dire need of a replacement. I’ve had it for something 5 or 6 years, so its time has come.

Obviously I do a lot of Photoshop work, so I need a machine that’ll be able to keep up with that. I was thinking of getting something like this with a 500GB HDD and 3GB RAM. Does anyone have any experience with these built-to-order deals? Do they end up working well? Oh, and can someone give me advice on what processor and stuff to choose? What power protector to choose?? I am not a computer person at all.

Too scared to switch over to the Macs. I’ve been using Windows all my life, so you know.

edit: So uh apparently my laptop is infected with this horrible smitfraud c.coreservice thing and when I google that all I get are horror stories. Apparently I shouldn’t even be connected to the internet with this thing on my laptop, but I can’t even get on the internet with my desktop (the wireless adapter decided to stop working) so this is The Only Way. I’ll probably reformat this thing tomorrow since I don’t want to go through all the drama it takes to get smitfraud off so hopefully reformatting will do the trick. It’s not like I have anything special on this machine anyway. Ugh, what a headache.