Yes, you have to use the goldcard method. But once you have the goldcard part done, the rest is just the same like my guide I didn't include the goldcard method to protect the user's files.
First of all, welcome to Android world You did it excellently my friend. Flashing a ROM is NOT like installing something. It clears the previous ROM and writes the new one. So you don't have the previous ROM anymore. Tadaa~

Don't use advance task killer. Take my advice and use the best application. Search in market for "TasKiller" and use that. This is what you should do after that:

In the settings, allow autokill (check it). Then, in the list, allow all the applications that you use all the time (phone, home, messaging, clock, etc)
To allow them, long-tap on the application and add to ignore. Once you have done this, go to the home screen. Add the widget which is called "TasKiller". Note that it creates 3 types of widgets. Use the 1x1 widget. Now, on your screen, tap that widget and see what it does. It will even tell you how much memory you have left Now you will not feel the low memory problem anymore.

g'day guys, wish 2 check, is this guide applicable for Motorola Dext as well? Thanks