raggie33,
Can't help you with Yoper Linux or your divx player. Could be the player itself, video card (or shared video memory if no physical card is installed), various config settings.
But if you (or anyone else) wants to dabble in Linux without the commitment, try one of the Live CD distributions. Knoppix and Mepis come to mind, they are both Debian based and Live CD's. This means you go download them (both large downloads) or buy a cd for really cheap.
Once you have a viable cd, simply place it into your cd-rom (hopefully it's a bootable cd-rom) and reboot your machine. The install is a no-brainer, basically they do everything without you having to do much more than watch. Since they are Live CD's, nothing gets installed onto your hard drive. Though they do have the option of actually loading onto your hard drive if so desired, but the default is to NOT load anything onto your hard drive. Anyway, it gets loaded into memory (ramdisk). The more memory your computer has, the better things will run.
Knoppix has a nice little (easy to use) utility that allows you to save your configuration settings, like e-mail, Internet connect, favorites, etc to a floppy disk. Which you can use the next time you boot into Knoppix. Unfortunately, Mepis does not.
If they don't work out, simply remove the cd and reboot your computer. Your computer will boot up as normal with whatever operating system you happen to have on your hard drive.
http://www.knoppix.net/
http://www.mepis.org/
Mike