Well, if you're not going to use 4gigs of ram, then I wouldn't worry about it. Many applications, including WindowsXP like to get their hands on as much ram as possible. If you have more physical ram available, and tell your OS not to use virtual memory (making the harddrive act as extra ram), then your applications will load much more quickly.
See this
link for more info.
What is Virtual Memory?
A program instruction on an Intel 386 or later CPU can address up to 4GB of memory, using its full 32 bits. This is normally far more than the RAM of the machine. (The 32nd exponent of 2 is exactly 4,294,967,296, or 4 GB. 32 binary digits allow the representation of 4,294,967,296 numbers — counting 0.) So the hardware provides for programs to operate in terms of as much as they wish of this full 4GB space as Virtual Memory, those parts of the program and data which are currently active being loaded into Physical Random Access Memory (RAM). The processor itself then translates (‘maps’) the virtual addresses from an instruction into the correct physical equivalents, doing this on the fly as the instruction is executed. The processor manages the mapping in terms of pages of 4 Kilobytes each - a size that has implications for managing virtual memory by the system.
What is loaded in RAM?
Items in RAM can be divided into:
The Non-Paged area. Parts of the System which are so important that they may never be paged out - the area of RAM used for these is called in XP the ‘Non-Paged area’. Because this mainly contains core code of the system, which is not likely to contain serious faults, a Blue Screen referring to ‘Page Fault in Non-Paged area’ probably indicates a serious hardware problem with the RAM modules, or possibly damaged code resulting from a defective Hard disk. It is, though, possible that external utility software (e.g. Norton) may put modules there too, so if such faults arise when you have recently installed or updated something of this sort, try uninstalling it.
The Page Pool which can be used to hold:
--Program code,
--Data pages that have had actual data written to them, and
--A basic amount of space for the file cache (known in Windows 9x systems as Vcache) of files that have recently been read from or written to hard disk.
Any remaining RAM will be used to make the file cache larger.
Why is there so little Free RAM?
Windows will always try to find some use for all of RAM — even a trivial one. If nothing else it will retain code of programs in RAM after they exit, in case they are needed again. Anything left over will be used to cache further files — just in case they are needed. But these uses will be dropped instantly should some other use come along. Thus there should rarely be any significant amount of RAM ‘free’. That term is a misnomer — it ought to be ‘RAM for which Windows can currently find no possible use’. The adage is: ‘Free RAM is wasted RAM’. Programs that purport to ‘manage’ or ‘free up’ RAM are pandering to a delusion that only such ‘Free’ RAM is available for fresh uses. That is not true, and these programs often result in reduced performance and may result in run-away growth of the page file.