A clean design, nice simple, clear and professional looking. The sidebar on the right needs some attention as the font is different.
Its a shame the website is constructed using tables. Take a look at using CCS (Cascading Style Sheets). It will provide better accessibility to different web browsers / devices, a quicker website and will be much easier to manage.
Color scheme is a bit bland but works. Your use of tables to list what features are available per plan could use some touching up. Add some visual to them so they are not so boring. They seem sort of just thrown on the page with not much planning or thought. Your sign up form has to be skinned to look like your site. You have gray tones through-out your entire site and then when you click to sign up, you practically get blinded by the intense radiation style green sign up form. WOW - soo bright. Work on changing it's color to match the site and try throwing up a header on it as well.