You probably have an answer already, but for future ref:
Go to the the Madrake rpm search page (
http://rpms.mandrakeclub.com) and type the name of the missing shared library (the .so file) into the box. You must remove the trailing digits and dots so the file name ends with ".so". This will tell you what package provides that file.
Find a line matching you distro version and use that pagage name in a urpmi command. It is best to leave off the version numbring so you would use urpmi "libgtop2.0_0-devel". You must the repeat the urpmi for gdesklets.
These errors are caused by faulty packages that do not list their dependancies quire correctly.
PS I have not got gdesklets to work yet!