Re: Hardware demands
You need to understand that newer doesn't mean better or faster.
The trend in Microsoft Windows since Vista has been to favour appearance and bling at the expense of performance. Vista, 7 and 8 need huge hardware, and I'm sorry to say Ubuntu has been following suit.
The recommendations above regarding Lubuntu and Xubuntu are very good. I myself am running Lubuntu 12.04, and you can see the technical specs of my dinosaur (hardware dates back to 2003) below, in my signature. The lighter interface does make a huge difference.
AMD Athlon XP 2000+ | ASUS A7V8X-X | 2GB DDR | ATI Radeon 7500 64 MB | Lubuntu 12.04
AMD Phenom II 960T | Asus M3N-HT Deluxe | 4 GB DDR2 | Onboard Graphics | Ubuntu 14.04
Dell Inspiron 15 5547 | i7-4510U | 8 GB DDR3 | Ubuntu 14.04