BSOD after Installing New Graphics Card - Please Help!

My system configuration is as follows -

CPU - AMD Athlon II X2 240
Motherboard - Biostar TA785GE 128 MB Sideport
RAM - Kingston 2 GB DDR2 8ooMhz
HDD - Seagate 250GB SATAII 7200.12 Series
ODD - Sony DVD-RW
OS - Windows 7 Ultimate 32 Bit

I recently bought a used Palit GeForce GT 240 512MB GDDR5 from a friend.
After installing the graphics card I am getting BSOD quite often. This happens only when I am gaming.

Please have a look at the minidump logs below -

Minidump.7z

Click to expand...

I have a cheap Zebronics 400 Watt PSU which I am guessing is the problem.

Is it?

Thanking you for taking a look

Hi I don't think you have enough ram to run windows 7.