Ubuntu uses the Gnome desktop. I like KDE. Every time I have tried Gnome, I ended up switching to KDE. Kubuntu is not as well polished as SimplyMEPIS 7.0 The Mepis utilities make the OS much easier to use with one exception. The Nvidia driver. Ubuntu has an easy Nvidia driver installer. If you don't need it for 3D, you will be just fine. If you want it in Mepis, be prepared to have to do it one of two ways and fix the X system after the first time.
In Mepis you only have to enable a repository and install the necessary packages (programs) to have full multi-media with the non-free software.
An important thing to do, when you load the live CD/ROM, hit F3 and choose your resolution at that point. Load the OS live and then install. It should then be in your preferred resolution. Text sizes should be perfect for your system.
I had trouble with an ASUS P5B Deluxe motherboard due to the Intel 965 chipset. I had to trick it to get it to install. But it's working great as my main system now. On older hardware, it's flawless on the install. Other chipsets may not be a problem either.
I do all my surfing and email in Linux. I game in Windows 2000. So several of my systems are dual-boot. Load Windows first, then Mepis and choose the default locations for Grub. It should pick it up just fine. The Mepis Lovers forum should have all the info you need for your questions.
On any hardware, but especially older systems, try AntiX 7. it's using the Mepis utilities with the Fluxbox desktop. You can use the Ice weasel/Fire Fox browser and even Thunderbird no problem. Fluxbox is a bit different. Use the right-click to get the main menu up. Very fast and smaller install. Works great on new hardware too.