Running out of memory as in harddrive (hdd) space, or RAM? If it's an hdd issue, you can get an external hdd - Microcenter has 1Tb drives for <$70.
As for PCs, the big problem is that there are very few Windows 7s around. I just bought a new laptop this past fall, and it was quite a production finding a Windows 7 with the specs I wanted (my laptop is my gaming machine, and needed a certain level of specs). If you want a laptop, get on Dell's website where you can custom build a laptop. You'll want at least a i5 processor, with minimum 6gig of ram, and 750gig of hdd space. That's the specs on my laptop, and even gets laggy and frustrating when editing photos for our webstore. Any less specs than that, and you'll be banging your head onto the desk cos it's so laggy and slow.
Even though I'm a PC user, for graphics, I always suggest Macs. Their integration and architecture for handling graphics and color calibration has always been superior to PCs. And as for the above post, the Apple Genius bar are no longer geniuses. They're just average schlub workers who know no more about computers than my mother. The blank stares I received when I mentioned kernel errors on my iPhone were pretty epic =P. There's a reason why professional graphic artists use Macs, and not PCs. Plus, the monitors with Macs, because they're traditionally used by graphic artists, are a better quality, with better color calibration.
A low to medium range Macbook Pro would be fine if you want to pay that much money. The new Haswell processors have some pretty awsum benchmarks, and I don't think any PC laptops have them yet. You'll get much better performance out of a mid-range Macbook Pro than you would even a higher-end PC. All my professional graphic artists and fine artists friends only use Macs.
I bought an $8000 dell laptop which also failed, so it goes both ways.
