Call of Duty titles on the PC have always been a bit more on the lenient side when it comes on the system requirements and Modern Warfare 2, with a few exceptions, is no different. On the processor front, single-cores are still supported, 1GB of RAM is now the minimum whereas Call of Duty 4 required 512 MB from XP users and a slightly higher amount from Vista users. Those who have a NVIDIA GeForce 6600GT or ATI Radeon 1600XT or something much better (which you should) will be covered. Though it isn’t listed on requirements on Modern Warfare 2‘s Steam page, IW’s Robert Bowling has confirmed that Windows 7 is supported as well.
Another recommendation that probably hasn’t been listed for modern first-person shooters on the PC for a while is for hosting, presumably if you want to host your own game for the matchmaking service that is be used for Modern Warfare 2 on the PC which states, “To host Co-op or MP matches, a 2Ghz dual-core or better processor is recommended.” Implying that the amount of players on a hosted server will be dictated by the power of the host’s PC. According to the Steam hardware survey as of September of this year, 23% of people are still rocking single-core processors. To say the least, PC players who enjoy playing Call of Duty 4 on stable dedicated servers that are able to hold up to 40 or more players may have to to take some time to adjust to limits of the individual hosting any server on Modern Warfare 2.