So far, 1GB seems to be the spot to be. However I do find consumers easy attracted to more is better devices.
-> About your question. If the mechanical and slot and such fits then you need to find out how many Watts this card takes and compare it to your old card. If it's close, it should be fine.
Will my HP Pavilion Elite M9500y with a NVIDIA GeForce 9500gs support the MSI N630GT-MD4GD3 GeForce GT 630 4GB 128-bit DDR3 PCI Express 2.0 x16 graphics card. I would like to upgrade from the 512 installed and this card seems to do the job and the price is right.