Lots of people. Check out xfire website for some number of hours some players logged in. If you want to play the game competitively, check out this new site. It's still new, so create an account and expand it.

http://flanknet.com/index.php

Of course there are still players online. Not all PC users like CODWW and MW2. If you want to player this game competitively, check out this site to make matches online with people around the world. Warning: The site is still new, so create an account and start.

http://flanknet.com/index.php

SWAT 4 TSS because of the better co-op gameplay and the wider selection of of non-lethal weapons to use.

For playing in a SWAT 4 community, check out:

http://www.frostysplayhouse.net/

For playing SWAT 4 competitvely, check out:

http://flanknet.com/index.php

For online community, check out this:

http://www.frostysplayhouse.net/

For competitive gaming, check out this:

http://flanknet.com/index.php