Q: how do i find out what generation my ipod is?  it is old...2005

2005 is probably 4th gen or 5th gen (unless it's an iPod mini).  If it can play videos, it is 5th gen.  If it has a color display, but does not play videos, it is 4th gen.

This Apple document has a list of all the iPod models

http://support.apple.com/kb/ht1353

as well as this one

http://www.everymac.com/systems/apple/ipod/index-ipod-specs.html

NOTE:  iPods are not always referred to by the "generation" number, and each type of iPod as its own gen numbers.

Will my 5th genration iPod work with "30-pin docking music ssystems?

That is the correct type of dock connector for a 5th gen iPod.  Whether it works with an accessory or not depends on the accessory.  You'll have to look at the manual or other documentation for that product, to see what iPod models are compatible.