Will I lag?

Here are my specs:

Windows XP
Pentium 4 2.20GHz
768 MB RAM
GeForce 4 MX4000 128mb

Thanks for the help.

Those computer specs are fine, except IIRC the video card you have may struggle a bit at the higher resolutions or with anti-aliasing on. Besides that though, should be fine for Guild Wars. Although I don't know why you needed to ask us that since game system requirements are usually printed on the box...