The following link will take you to the Microsoft article concerning upgrading your XP RDC clients to the Windows 7/Server 2008 R2 compatible version. Take note of the known issues section.
Upgrading your RDC clients will allow you to take advantage of the following, should your OS support these options:
Web Single Sign-On (SSO) and Web forms-based authentication
Remote Desktop (RD) Web Access now uses forms-based authentication to improve the user experience. Web SSO makes sure that after a user is logged on, no additional passwords are required for RD Gateway, RD Session Host servers and RemoteApp programs.
For security, Web SSO requires remote applications to be signed using a certificate from a trusted issuer.
Access to personal virtual desktops by using RD Connection Broker
Users can access personal virtual desktops when they use the new Remote Desktop Virtualization Host in Windows Server 2008 R2. Personal desktops are assigned to users on a one-to-one basis and maintain state over time.
Access to virtual desktop pools by using RD Connection Broker
Users can access virtual desktop pools when they use the new Remote Desktop Virtualization Host in Windows Server 2008 R2. Pooled desktops are shared between multiple users, and all changes a user makes are typically rolled back when the user logs off.
Status & disconnect system tray icon
A single system tray icon enables users to see all of their remote connections. The user can disconnect all or individual connections that use this icon. The icon appears only when opening RDP connections which are associated with a RemoteApp and Desktop Connection feed.
RD Gateway-based device redirection enforcement
In Windows Server 2008, it was possible for non-Microsoft Remote Desktop clients to override the gateway device redirection controls. In Windows Server 2008 R2, device redirection settings are defined in RD Gateway and can be configured not to be overridden.
RD Gateway system and logon messages
System and logon messages can be added to RD Gateway and displayed to the remote desktop user. System messages can be used to inform users of server maintenance issues such as shutdowns and restarts. Logon messages can be used to display a logon notice to users before they gain access to remote resources.
RD Gateway background authorization & authentication
Background authentication and authorization requests are performed after a configured session timeout is reached. Sessions for users whose property information has not changed are not affected, and authentication and authorization requests are sent in the background.
RD Gateway idle & session time-outs
Configurable idle and session time-outs with RD Gateway provide better control of users who connect through RD Gateway. An idle time-out lets the user reclaim resources that are used by inactive user sessions without affecting the user's session or data. This helps free up resources on the RD Gateway server.
NAP remediation with RD Gateway
NAP remediation allows you to manage remote clients by updating them with the latest software updates and settings. This helps keep remote clients in compliance with network security policies.
Windows Media Player redirection
Windows Media Player Redirection enables content hosted in Windows Media Player to be redirected to the client for decoding on users’ computers. This improves the quality of the video and makes sure that video and audio are always in sync. This works for both full Windows Media Player and Windows Media Player controls hosted in Web pages.
You can redirect audio recording devices such as microphones on the client computer. This is ideal for applications such as Windows 7 voice recognition, and applications that record audio.
Multiple monitor support
In Windows Vista and in Windows Server 2008, Terminal Services supported only monitor spanning. Remote Desktop Services now includes multiple monitor support for up to 16 monitors, and works for both Remote Desktop and RemoteApp programs.
Note For connections with multiple monitor support enabled, AeroGlass support is currently not supported and will be turned off.
Enhanced video playback
Bitmap acceleration improves the remote display of graphics-intensive applications such as PowerPoint, Flash, and Silverlight.
The download link for each version is at the bottom. As always, make sure you test before deploying to your clients.