I can rapidly prototype code but I get tripped up on design

Guys,

I'm a big fan of rapid prototyping. Get your startup idea up in a week or two and get a feel for how people like it. I can easily create the code (php/jquery,etc) but I always get tripped up on the design.

I'm not entirely sure what the resource I'm looking for is, but I want to find tools to help me quickly put together CSS spreadhsheets with decent looking designs.

Are there generators with web 2.0 design styles where you can click which features you want and it will generate designs for you?

I'm not looking for a design that will be the design the site will have in two months, just something that people can look at and not think this website is a complete joke.

Maybe something like http://www.web20generator.com that's less of a joke and has more features.

I've been studying at designfromscratch.com to help get some principles, but I'm not a design guy and I'd rather pay for design after my concepts are solid.

I'm not sure if I'll get laughed off the boards for this, but any tips/ideas would be appreciated.