If you’re used to using unix, & as you say you’re wanting to avoid a “dummies” version, i’d avoid Ubuntu. That’s much more tailored to people unused to Unix command line etc. & I suspect you’ll find Ubuntu a bit frustrating.
For what you say you’re wanting to do, the desktop is going to be less important than the developer toolset. I’d suggest looking at CentOS (basically Red Hat Enterprise Linux (RHEL) with the Red Hat branding removed), or Fedora. (disclaimer, I work for Red Hat so would say that wouldn’t I 😉
You’d also find the same developer toolsets on some of the other more Unix-like distro’s such as SuSE & Debian.
I can’t really offer any advice on running it on your Vista laptop. (I’ve never used a windows desktop). What i would suggest is avoiding using a Live image on a USB key. For dev. work you’ll be wanting something a bit more permanent, even starting out. If you can use some form of virtualisation & run it in that, go for that. Alternatively, look at using a USB drive to store the linux filesystems & create a bootable USB key that runs linux from the USB drive. That way your vista is left untouched.