elksman, it is *normal* that XP mostly does not see all 4 GB. reason is the memory management (already by the BIOS) which mapps certain PCI-ressources into the most upper memory region. this is needed, because XP32 bit could not read any addresses above 4 GB,
but to loose a whole GB is unusual ... my experience is 3,75 GB are available.
i would not change the 2 GB sticks to 1 GB because you're left with 2 GB in total then (i'd assume this is a dual bus-memory requiring two identical sticks) - try to get support from IBM or a specialist for BIOS settings to reduce the amount of *stolen* RAM
christian
edit: any onboard (shared memory) video card could also grab memory ....
but to loose a whole GB is unusual ... my experience is 3,75 GB are available.
i would not change the 2 GB sticks to 1 GB because you're left with 2 GB in total then (i'd assume this is a dual bus-memory requiring two identical sticks) - try to get support from IBM or a specialist for BIOS settings to reduce the amount of *stolen* RAM
christian
edit: any onboard (shared memory) video card could also grab memory ....
and remember: only a CRAY can run an endless loop in just three seconds.