Depends on what you want the card for honestly
If I am not mistaken a 6150 LE isn't even an actual graphics *card*.. its more like an integrated graphics accelerator.
The memory on the card itself.. its like this. A good card is a good card.. due to stream processors, memory clock, processor clock, and possible resolutions. The memory they put on them can be deceiving. Having a really bad video card with 1 gig of ram is like putting a spoiler on a Yugo?
Just by putting a physical card in it, you'll be better off, but the 9400 is a low end card of the 9 series.
The features and benefits of your accelerator :
http://www.nvidia.com/page/gpu_mobo_features.html
The features and benefits of the 9400gt. :
http://www.nvidia.com/object/product...9400gt_us.html
I still would recommend going with a 9600GT or better, if any way possible.