So you decided to learn something about Terminal Services or as it is called now - Remote Desktop Services. Where do you start. First you have to decide what version are you planning to work with. If you are new to the TS world I would suggest to Start with Windows 2003 and only after engage the 2008 version. Keep in mind that while the difference between Windows 2003 and 2003 R2 in terms of Terminal services is marginal, there is a big difference between 2008 and 2008 R2. I personally would recommend to go for those two books on the topic:

Terminal Services for Microsoft Windows Server 2003: Advanced Technical Design Guide (Advanced Technical Design Guide series) from Brian Madden

and for Windows 2008

Windows Server® 2008 Terminal Services Resource Kit by Christa Anderson (Author), Kristin L. Griffin (Author)

the disadvantage of the first book is the lack of electronic copy of the book. So you cant do searched within the content of the book. In case it is important for you, you might take a look at this one:

Microsoft® Windows Server(TM) 2003 Terminal Services (Pro-One-Offs) (Paperback)
by Bernhard Tritsch

 However always keep in mind that the actuall "build in" Help in both Windows 2003 and 2008 include a lot of valuable material, so unless you need a book to read on a train you can stick to Windows help with confidence.

So you got the books and now you need a Lab to try and test everything. So lets start with the hardware. A good choice would be a computer with at least 4 GB for Windows 2003 and 8 GB for Windows 2008, if you want to play with Windows 2008 R2 keep in mind that your CPU must be 64bit! Most of todays computers support this kind of configuration. On the hard disc - 100 GB should be sufficient. For CPU - go for at least a Dual Core CPU. If you already got a notebook or a computer with above spect but it is your dekstop computer and it runs at least Windows Vista or Windows 7 you can just make a Dual Boot to VHD file. The process is very well described here:

http://blogs.technet.com/keithcombs/archive/2009/05/22/dual-boot-from-vhd-using-windows-7-and-windows-server-2008-r2.aspx

Kepp in mind that if case you already have a running system you will need more hard disc space.

Software: here you have plently of choice - for OS you can use the most common Windows XP, Windows Vista or Windows 7. You will need a virtualization software. Here you have many choices but I would choose from either VmWare Workstation or Microsoft Virtual Server. The first one cost about 180 USD the second one is free. First one is more convinient and has better management tools, the Virtual Server might be a better choice technically since it supports the very common VHD format and in fact you can find a lot of those VHD prepared virtual environments online. So let consider we go with Microsoft Virtual Server:

http://www.microsoft.com/windowsserversystem/virtualserver/

As soon as you installed it download the W2003 VHD fils (the virtual boxes for W2003)

http://www.microsoft.com/downloads/details.aspx?FamilyID=77f24c9d-b4b8-4f73-99e3-c66f80e415b6&displaylang=en

Look for Webcasts on the Windows 2003 Terminal Services Topic

http://support.microsoft.com/default.aspx/kb/810589

Just look for "Windows 2003 terminal services webcast" in bing.com
As well I have some collection of Webcast links on my website:

http://www.pubforum.info/welcome/W2K8R2TSRDSVDI/tabid/73/Default.aspx

Here is the place where a lof of resources are put together:

http://www.microsoft.com/windowsserver2003/technologies/terminalservices/default.mspx

When you are comfortable with Windows 2003 move on to Windows 2008:

http://www.microsoft.com/windowsserver2008/en/us/rds-product-home.aspx

And finally... if you are in Europe - I'm doing a Master Class in many European capitals - most are free:

http://www.rds999.com

P.S: when you install an evaluation copy of W2003 for testing you have plently of time to check out
all the features in the 210 days (120 + 90)

http://www.microsoft.com/windowsserver2003/howtobuy/licensing/ts2003.mspx

P.S.S: Technet Plus does NOT have TS CAL's, MSDN does