Forget Ubuntu, its just stuffed with bloat ware these days, best to go with Linux Mint, as while it is based around Ubuntu it has none of the rubbish that Ubuntu itself comes with these days.

I would also suggest that you wait for Windows 10 which is due out later this year, as the technical preview is great, and with the features to be added shortly it is a genuine replacement for Windows 7. (Vista was a disaster which was solved with 7, and 8 was also poor which 10 solves)

If you don’t want to wait for 10 go for 7 as its way better than XP, and takes up no more resources. (I still have XP available in a virtual environment but I haven’t used it for years (One of these days I will finally get round to uninstalling it)

Hope this helps

Bill