I don't think this question has been asked before.

I have been given an old(ish) HP PC from the parentals. Unfortunately the bloatware has made it virtually unusable, and I'm wondering if it might be worthwhile giving Linux a crack instead of reinstalling Vista?

If so, which distro? Does linux still even exist?

I want to browse internets, watch internet porn, upload photos to fb and edit the occasional word document.

Cheerio

I think Mint is more popular than Ubuntu now too. Might want to check that out as well.

I've ordered USB drives of Ubuntu and Kubuntu. Aside from the GUI thing, are there any compatibility issues with programs? Is there more available for Ubuntu than Kubuntu?

I've ordered USB drives of Ubuntu and Kubuntu. Aside from the GUI thing, are there any compatibility issues with programs? Is there more available for Ubuntu than Kubuntu?

Nope, no compatibility issues, same programs available more or less - although KDE does tend to have some apps specifically developed for KDE. I'm sure you can find ways to run them though.