Question : Problem: Upgrading to Vista from XP

my friend is upgrading his computer from xp to Vista. his computer currently has 256 MB of RAM. the only information about his computer that he gave me is the following:
Gateway Pentium 4
CPU 2.60 GHz
E-4100 Series
and a bunch of number he found in the back of his computer: GM MSATX PNT MDW500X

I want to know specifically what kind of memory is needed to upgrade to 1GB and also if his computer is capable of accepting as much memory

Answer : Problem: Upgrading to Vista from XP

Computer will hold up to 4GB
Memory that will work for sure
CORSAIR MEMORY INC.
- Corsair Value Select - Memory - 1 GB - DIMM 184-pin - DDR - 400 MHz / PC3200  MFR#VS1GB400C3 Should sell in the $59.00 range
- Corsair XMS ProSeries - Memory - 1 GB - DIMM 184-pin - DDR - 400 MHz / PC3200 MFR#CMX1024-3200PRO  Should sell in the $129.00 range

About any generic  1GB DDR PC3200 128MX64 NON ECC 184DIMM UNBUF CL3 memory should work in this pc.