At the $1500 price point, I'd do an Intel Build.
As for the monitor, if Photoshop is the primary consideration, you'll want to avoid a TN panel. The entry point for n IPS panel is the Dell u2410. It can usually be found "on special" for about $530.
Watch sites like techbargains.com and fatwallet.com for the specials....otherwise its $599
I would note that my $1,500 budget includes the purchase of the monitor. I'm willing to add a little more Cash to the equation if it merits it.