Heya, I'd love to give some feedback.
First of all, the page load is really slow (1m 13s just now) - 61 requests, 485.7 KB total.
The idea seems very interesting (private social network for a business) and I really like the invitation letter at the bottom.
The helix ribbon at the top is totally random and doesn't provide anything meaningful. It also pushes the attention-grabbing content below the fold.
I think you guys got a cool idea and the overall design (minus the helix) is pretty good. The vision could do with some rephrasing to better enunciate the purpose (what's this, what's this for).
I'd suggest you go download Firefox and the following plugins: Firebug, Web Developer, YSlow, PageSpeed.
The first thing I'd do if I was you is run a YSlow benchmark (to see what needs improving - they also provide links to the theory behind the improvements and things you can do).
At the moment the current benchmark is:
Grade C Overall performance score 70 Ruleset applied: YSlow(V2) URL: http://open-collar.com/
F Make fewer HTTP requests
F Use a Content Delivery Network (CDN)
A Avoid empty src or href
F Add Expires headers
F Compress components with gzip
A Put CSS at top
B Put JavaScript at bottom
A Avoid CSS expressions
n/a Make JavaScript and CSS external
A Reduce DNS lookups
A Minify JavaScript and CSS
A Avoid URL redirects
A Remove duplicate JavaScript and CSS
F Configure entity tags (ETags)
A Make AJAX cacheable
A Use GET for AJAX requests
A Reduce the number of DOM elements
A Avoid HTTP 404 (Not Found) error
A Reduce cookie size
F Use cookie-free domains
A Avoid AlphaImageLoader filter
A Do not scale images in HTML
A Make favicon small and cacheable
Good luck :)