For learning purposes you may find that running in a local virtualized environment allows for greater flexibility, thus accellerating your learning. Where networking and internet technologies are concerned, you can easily configure multiple machines and work directly on their interaction, without having to worry about hardware expenses.
Depending on what you are working on, you may find that the virtual infrastructure presents you with some unique limitations or challenges, but as you overcome them they will only add to your experience and expertise.
By using snapshots you can easily revert any changes you commit, giving you additional freedom as you want to try out new configurations.
The bottom line is that virtulization is a very good tool for learning, development and testing.
Unless you have a reason to use the 64-bit release, you may as well start with the i386. It can be downloaded from most sunsites, such as the one at University of Oslo, or any other Debian mirror.
If you are in Europe, this is a good place to get the latest ISO files for i386: