
Originally Posted by
grss1982
^^ As stated by
muzikfreakah, if you're using Windows XP you're only going to see/be able to use about 3GB of your 4gb of RAM.
If you want to make full use of the 4gb RAM, you either use Windows Vista, Linux or BSD.
Hope that helps.
BTW, let me juts re-phrase my statement above. 
According to this link: Memory Limitations of 64-bit Versions of Windows XP
The 64-bit version of Windows XP can use 4GB or more of RAM.
Code:
Memory Limitations for 64-bit Windows XP
•Windows XP Professional for 64-bit platforms supports 16 GB of memory.
I'm assuming that most of those reporting problems with 4GB RAM are using the 32-bit version of WIndows XP.