Looking at the requirements for that game,
Street Fighter IV (4) System Requirements Quote:
Minimum System Requirements
OS: Windows XP/Vista
Processor: Pentium 4 @ 2 GHz
Memory: 1 Gb
Hard Drive: 10 Gb free
Video Memory: 256 Mb
Video Card: nVidia GeForce 6600 / ATI Radeon X1600
Sound Card: DirectX Compatible
DirectX: 9.0c
Keyboard
Mouse
DVD Rom Drive
and that all you have is the Intel onboard graphics, basically if you want to play that game (or for the most part anything more than solitaire) you're going to have to get a video card. Intel graphics have come a long way in the last couple of years, but they are still nowhere close to even an entry level video card for games.
Here are the full specs for your computer,
Acer Support - Veriton M460 Specifications
Looking at the dimensions of the case you should be OK with just about any PCI-E card, short of the 10-11" long high end cards. Another small problem is that if you decide to get a video card you are going to be severally limited as to what to get due to the max 300W power supply in it.