I've done everything I can with the Enviroment variable settings. Why can't I run Minecraft faster?

I have Windows 7 Premium running on an AMD Athlon(tm) 64 Processor 3500+ 2.19GHz, 32-bit Operating System, and 1.5 GB of RAM?

There are a few things you can do I'm just gonna make a list.

1. Don't play full screen
2. Stop some programs from running in the background
3. Change the windows 7 theme to windows xp
4. Make a ram disk.

That is all I can think of but these in combination will make it run faster