Sorry NO on the APU, APUs suck even with a GPU added (numerous articles on the benchmarks on them) because APUs are low budget, low demand, low cost solutions for the 90% other use of PCs (Youtube, Facebook, Word, etc.). Gaming requires much more hardware performance, and STARTS at $700 normally for a system that can play 1080P (1920x1080), 50+FPS, on HIGH settings for any titles even 2013 ones. Per canirunit.com the specs for GW2 are:
Minimum
CPU: Intel Core 2 Duo 2.0 GHz, Core i3, AMD Athlon 64 X2 or better
CPU Speed: Info
RAM: 2 GB
OS: Windows XP Service Pack 2 or better
Video Card: NVIDIA GeForce 7800, ATI Radeon X1800, Intel HD 3000 or better (256 MB of video RAM and shader model 3.0 or better)
Sound Card: Yes
Free Disk Space: 25 GB
Now you could try to skim a bit, and get a i5 Desktop from Slickdeals.net for around $349 , then add a Nvidia 750Ti for $120 or so (as it only takes 300W) but there is no way to get $400 gaming PCs, if you have to be that low GO CONSOLE. Besides the point is if you spend that money today ($400) do you need to shell out another $300 in several months for a new parts because the ones you got can't "perform" on the new game you want to play? Consoles last 10 years, so they are better 'gaming only' investments.