Hasta La Motion!

Hi guys here what i have so far i hve some money i would lie to upgrade my ass old pc, i am using it for just learning but when i am using cinema 4d and doing some simulation would get out of memory so i would like to gets some more but i don’t know if i can add more. Can you look at my spec and tell me what can i do and how much i can add. i am ruining 64 bid cd4 on xp pro 64 bit. Should i install windows 7 or is my pc to slow for it or will it use to much memory. Thanks guys.

CPU
Processor : AMD Athlon(tm) 64 X2 Dual Core Processor 4000+
Speed : 2099 MHz
Model : x86 Family 15 Model 107 Stepping 1
Processor ID : 178BFBFF00060FB1
Vendor Identifier : AuthenticAMD
Socket Designation : Socket AM2

Mainboard
Bus(es) : AGP PCI IMB USB i2c/SMBus
MP Support : 1 CPU(s)
Model : M2A-VM
Version : 1.XX
Serial Number : 123456789000
BIOS Version : ATI – 42302e31
BIOS Date : 12/19/07
BIOS Vendor : Phoenix Technologies, LTD

Memory Info ddr2 pc2-5300 noneccc dimm
Total Physical Memory : 2.00 GB
Free Physical Memory : 2.00 GB
Maximum Page File : 4.00 GB
Free Page File : 4.00 GB
Page File : C:\pagefile.sys
Initial Size : 2046
Maximum Size : 4092
Allocated Memory Load : 13 %