허니몬의 IT 이야기/리눅스 이야기, 우분투
이 방법은 그리 추천해드릴 상황이 아닌 것 같습니다. 가급적이면 우분투 64bit desktop 버전을 설치하시길 추천합니다. ^^; 저의 경우에는 9.04 64bit desktop 버전이 네트워크를 정상적으로 인식하지 못하는 문제 때문에 쓰지 못하고 있습니다. 9.10 버전도 마찬가지네요.


출처 : http://www.cyberciti.biz/faq/ubuntu-linux-4gb-ram-limitation-solution/
Ubuntu 4GB Ram Limitation and Solution

Q. I've total 8 GB RAM installed in my dual boot Ubuntu Linux 8.10 (32 bit) version HP workstation. But free -m command only shows 3291 (3G) memory. How do I use 8GB RAM under Ubuntu Linux?

A. You need to install Physical Address Extension (PAE) aware kernel under 32 bit Ubuntu Linux. It is a feature of x86 and x86-64 processors that allows more than 4 Gigabytes of physical memory to be used in 32-bit systems.

Without PAE kernel, you should see something as follows:
$ free -m


Sample output:
                   total       used         free     shared    buffers     cached
Mem:          3291        801       2489              0           95         342
-/+ buffers/cache:      363       2927
Swap:         1906          0         1906

You have two options here as follows:
Option # 1: Use 64 bit Ubuntu Linux

64 bit Linux kernel will take care of 4G or more memory. Just grab latest 64 bit version and install it.
Option #2: Install PAE enabled kernel

Open terminal and type the following command:
$ sudo apt-get update
$ sudo apt-get install linux-headers-server linux-image-server linux-server


Once kernel images installed, just reboot your workstation, type:
$ sudo reboot


After reboot, login into your system and type the following command to verify memory usage:
$ free -m


Sample output:
                   total        used         free     shared    buffers     cached
Mem:          8105       1292       6812              0          38           483
-/+ buffers/cache:       770       7334
Swap:         1906          0          1906


  ㅡ_-);; 오페라를 설치하고 나니까 apt-get update 할 때 공개키 때문에 충돌이 난다!!
  그래서 찾아보고 또 바로 포스팅!!
  GPG Error 처리 : http://ihoney.pe.kr/522