First you should determine what type of RAM do you have in both computer and if they are compatible.

Types of RAM are:

SDRAM (Synchronous DRAM)

It is a 3.3 volt, 168-pin SDRAM DIMM. But as processors get faster, new generations of memory such as DDR and RDRAM are required to get more performance.

DDR (Double Data Rate SDRAM)

DDR doubles the rate of data transfer of standard SDRAM. DDR is a 2.5 volt memorythat uses 184 pins in its DIMMs. It is incompatible with SDRAM physically, but uses a similar parallel bus.

Rambus DRAM (RDRAM)

RDRAM is a serial memory technology: PC600, PC700, and PC800.

SDRAM and DDR are different and not physically compatible. SDRAM DIMMs have 168-pins and run at 3.3 volts, while DDR DIMMs have 184-pins and run at 2.5 volts.

More information about RAM memory you can find here.