More than one place where you can limit the memory that XP will use. I run into this from time to time with persons that want to tweak Windows memory usage. Here's the usual limit settings.
1. "Table 28.18 lists optional parameters that you can append to the ARC paths contained in the [operating systems] section of the Boot.ini file. For example, the following optional parameters limit memory usage to 64 MB:
multi(0)disk(0)rdisk(0)partition(1)\Windows="Windows XP Professional" /fastdetect /MAXMEM=64"
More about BOOT.INI at http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/Default.asp?url=/resources/documentation/Windows/XP/all/reskit/en-us/prmc_str_masc.asp and ... google.com
2. On the msconfig page choose Advanced and one of the items will be 'Limit memory use to...'. Set it to your choice.
I have installed 1 Gig of Ram (2 identical 512 Meg Kingston Value Ram 3200 DDR chips)in my Win XP Pro SP2 machine. It is AMD 64 bit 3000+ chip with NVidia 128 Meg video Ram. ASUS K8Ne Deluxe motherboard. The Bios recognizes the full Gig of Ram but Windows only recognizes 400 meg. How can I get it to recognize all the Ram? I have switched out the ram into another computer to make sure it works and I have switched it out of one ram bank into the others on the motherboard to make sure it worked. Both RAM chips are working properly. CPUZ also recognizes the full Gig of Ram. Any help would sure be appreciated.