If those are your only 2 choices, then OpenSUSE 10.3
I think you should try SimplyMEPIS 7. It has been my favorite ever since it was released. Until then, i was an opensuse guy, and before that i used ubuntu.
simplymepis 6.5 wasnt amazing or anything an i never used it, but things have changed since then and no distro beats 7.
as jakec said, pclinuxos would be a great one too. If you like the feel of KDE (more similar to windows, start menu, etc.) then go for pclinuxos or simplyMepis
If you like the look of gnome, like what ubuntu uses, you could try PCLinuxOS gnome edition.
The easiest way to decide might be to download virtualbox and try out all the distros in a virtual machine and see which one you like best.