PMDG 737NG

I was thinking about purchasing a copy of this addon its MINIMUM SYSTEM REQUIREMENTS are:
– Microsoft Flight Simulator 2004 or 2002 Standard or Professional
– Pentium III 1.7 GHz PC
– 512 Mb RAM
– 32Mb 3D graphics accelerator card
– Hard drive space: 340 MB
– Monitor capable of 1024 x 768 resolution
– CD-ROM drive
– Sound card

I have a 256MB RAM and was wondering, if FS2002 only requires 128 MB of RAM why does one of its addond require 5 times more??

Will my 256MB be able to cope with this addon (without jumping)
Thanks in advance
Speedbird 12T