Windows has had QoS traffic management for a while now, but it used applications, IP addresses, and port numbers to determine which traffic got priority. That's both overkill and more complicated than you might need for your business network.
Starting with the latest versions of Windows, you can set traffic priority by Website address. This way, as a network administrator all you need do is set up policies by Website address, instead of digging around for IP addresses. So, for example, you could set the ZDNet Website to have a high-priority while locking down ESPN.
To do this, you first set up a QoS Policy on Server 2008 R2. The simplest way to do this is to use the GPMC (Group Policy Management Console).
The technology that makes this happen is Differentiated Services Code Points (DSCP). This is derived from an Internet networking standard, RFC-2474, that defines how a value in a TCP/IP packet header is set. It's used to determine how high a priority packets are given as they make their way around your network. Generally speaking, the higher the DSCP value you give a site, the higher its traffic priority is. So, for example, if you gave your company's Web site a DSCP of 63--the scale ranges from 0 to 63--traffic to that site will be much faster than to, say, ESPN with a DSCP of 0.
Sorry, I'd like to watch ESPN's Pardon the Interruption on my work computer, but with only so much bandwidth to around, it's really not practical for most businesses.
Exactly how much the traffic is throttled to a given site isn't determined just by its DSCP. In GPMC, you must also set how fast or slow a site's traffic is permitted in either KiloBytes per second (KBps) or MegaBytes per second (Mbps).
Once you set up your DSCP values and their corresponding throttle rates on the Policy Profile tab, you can assign them to URLs. These URLs can include wild-card characters. So, for example, you can slow down ESPN traffic no matter whether someone tries to get it using http://www.espn.com or http://espn.go.com. You can also specify a port number, although almost all Web sites use port 80 by default. You'll also want to select the Include subdirectories and files check box to apply the traffic management settings to all of a Website's subdirectories and files.
When sites compete for bandwidth, Windows uses tie-breakers. These start with DSCP, and then, from highest to lowest, are determined by host name listing order, IPv6 address, IPv4 address, and wild-card. So, when you build your policy, be sure to list the most mission-critical sites first by their specific URLs.
To make sure your policies are setup properly, Microsoft provides a handy QoS Traffic Generator, and examples on how to use it with its QoS Traffic Generator Example Usage.
On the Windows 7 client side all you need to do is click a few buttons and you'll be on your way. Click Start; Control Panel; Network and Sharing Center. Once there, pick the correct LAN connection. Then, once you're at the Local Area Connection Status window, click on Properties, make sure the QoS Packet Scheduler radio button is clicked on, and your should find that your Internet traffic usage is a lot more responsible, albeit not half-as-much fun, for users.