For version 1.11, your GTK+2 must be at least 2.14.
For version 1.10 (Linux), you need GTK+2, preferably in a fairly modern version. This should be installed on any Linux distribution less than about eight years old. For the Windows GTK2 build, the required libraries are included in the zip file; but you need Windows 2000 or later. If you are running an older version of Windows, you should probably use the GTK1 build, in which case you will need to install the gtkdlls1.zip file as well.
To build the programs from source, you also need Perl, and preferably GNU make. On Windows you will need various Microsoft files which are part of the Platform SDK (which is fortunately available free of charge from their Web site); and though it is theoretically possible to build in an MS development environment, for all practical purposes you will need MinGW. You can also cross-compile, which is currently the only method I still support.
To decide whether you want to upgrade, read the brief notes of the differences between successive releases in the CHANGES file.
You can make a donation via PayPal. The amount is up to you; if you want a suggested figure, how about fifteen euros/dollars?