Usually an IP camera comes with web setup interface. You could simply use that to set up IP address, username, password. There are brands like trendnet, zonet, axis, dlink, linksys, ...etc. If you live around frys from time to time they offer their airlink brand for sale. For other brands here is a link to newegg.com http://www.newegg.com/Store/Category.aspx?Category=288&name=Security-Surveillance
There is a review on maximumpc website on one of the trendnet ip cam, check that out.
Unless your dsl modem has a router build in, otherwise it won't work. Just like computers, IP cam is a device with a little computer with a cam build in. You need to type in the internal IP address (example: 192.168.1.254)to access the web setup utility. Since you probably need to access from outside, the web interface also give you the option to do so. It may require a little network knowledge though, not too hard.
If you are not going to do any direct recording to a desktop computer, then there's no need to install any software.
Of course the web setup utility has the option to upload pictures in jpg format and/or video clips mjpg or mpeg4 format (depends on cam) to a specified server, or email.