As a designer I would never hand over my designs to one of those chop shops. Any designer worth his salt can code his own designs. I don't trust the psd2html services to give me high-quality, semantic, robust markup and CSS.
You're probably more talented than you realize, but I wouldn't expect all designers to know html. I know a few designers that are amazing, but clueless with html. I think the skills are quite often mutually exclusive -- which is a good thing for you as the exception.
I've met a few talented web designers who don't grok html, javascript and css, but (so far) no product ux designers. Depending on the type of product you're building, someone like this may be exactly who you really need.
Working with a good ux designer will completely change your understanding of the role of design in product development. They can play a pivotal role in defining and shaping your product. And yes, a person with these qualities almost invariably can also code. Understanding the underpinning technologies of the web remains nearly inextricably entwined with understanding the design potential of the web.
As an aside, I think a platonic ideal founding team would have 2-3 people who share varying degrees of business, design and technical acumen. Each person has a defined role, but they also relate to their co-founders' roles in a meaningful way. Really understanding what it means to be GREAT at something often requires educating yourself enough to become mediocre at it. Completely partitioned specialization is for companies big enough to need HR departments.
