I'm new with Linux and started with Ubuntu 11.10, I installed it in my PC (Core2Duo 2Ghz, 512Mb Ram DDR2, integrated video in Motherboard), I know the requirements for Unity are 1Gb Ram so I decided to download a Desktop environment more lightweight, so I Installed LXDE, it loads very fast, compared to the 3.5 min from login screen to open desktop in Unity, but it freezes every time I open a single program, I can't even navigate in Internet, it freezes, sometimes for a pair of minutes and the graph at bottom right is all green as if iyt were using 100% CPU, it happens with every program.

As additional data it takes 3+ min to get from boot system selection screen to Login screen and 3.5 Min more to get into Ubuntu with Unity, with LXDE it turns to 30 secs aproximately.

Is Ubuntu + LXDE Desktop Environment Package = Lubuntu? or should I download Lubuntu directly instead?

I installed some other desktop environments, as Gnome but it doesn't log in, the screen just turns grey.

Should I get an older Ubuntu version?

I'm thinking about uninstalling Ubuntu but I'll try to deplete the options, thanks for your support.