Here is a list of the system requirements. The game can be put into window mode however, and shrunk to save some processing power. [Guild Wars 2 main page]
Minimum system requirements:
Windows XP Service Pack 2 or better
Intel Core 2 Duo 2.0 GHz, Core i3, AMD Athlon 64 X2, or better
2 GB RAM
NVIDIA GeForce 7800 or better (256MB of video RAM and shader model 3.0 or better)
25 GB available HDD space
Broadband internet connection
Keyboard and mouse
Guild Wars 2 really isn’t all that CPU intensive. Just about any computer should be able to play it at least half way decently.
And check out the "suggested by the author" links below for more!