If you are interested in getting an overview of Citrix product and see a quick demo, I would highly recommend the citrix demo site. http://www.citrix.com/English/ps2/demo.asp
You can get here by clicking Demo link on top of http://www.citrix.com/ hompage.
can find both flash based demo and live demos. I recommend you take a look at Flash based demos first if you are new to Citrix products. The on line live demo allows you to try the products yourself and try out features not covered by the flash based demos. You also find examples of third party applications running on citrix platforms.
especially like the demos that have side by side comparison such as Presentation Server Feature Spotlight: Speed Screen Progressive Display demo.
can also download a virtual appliance here. This is a new feature. I will try to talk more about virtual appliance in a separate post.