Oh, your computer must have a very old motherboard if it supports only 256 Mb of memory.
Nowadays, most computers support at least 1 Gb of memery so just open your computer's cover and look if there's any free memory slots. Also check from your motherboard's manual how much memory does it support. If you don't have the manual, you can download and install a software called Everest. It will tell you the model of your motherboard and you can then search Google.
I think 2006 and 2007 mods by Tony have also lower resolution textures. You can choose them from CSM (select mod and go to mod's configurables).