The cheapest graphics card you can play it on is an NVIDIA GeForce 510. Advent system requirements state that you will need at least 512 MB of RAM. To play Advent you will need a minimum CPU equivalent to an Intel Pentium 4 2.00GHz. You will need at least 230 MB of free disk space to install Advent.
Advent will run on PC system with XP / Vista /7 and upwards.