You will need to weight the bones to get the bones to move the mesh yes, but blender has a pretty good automatic weighting system so it's pretty much as easy as selecting a menu option. You don't need to worry about vertex painting and vertex groups, the auto system should sort that for you.
Just remember when you are exporting, if you export to .X you will need to run it through fragmotion and re-export it to .X from there for the weighting to stick, for some reason Blenders .X exporter doesn't apply the wighting properly for gameguru. but the exporter in fragmotion does.
Don't worry you can easily get fragmotion, and although it's a paid app, you can actually use it for free with no limitations, except for a smiley face and a bubble asking you to buy it popping up on the screen every few seconds, which considering the import/export stuff you need to do only takes seconds anyway doesn't really get in the way.
Sometime (probably the weekend) i'll see if i can do a quick video on how to get a character from blender to fragmotion and into gameguru in .X format.
One of the better tutorial series for learning character creation is Sebestian Lagues character creation series, most of it is valid for gameguru, however when you get to the walk cycle video, stop just before he starts showing how to create a path for it to walk along, that bit's not needed for gameguru.
https://www.youtube.com/watch?v=DiIoWrOlIRw&list=PLFt_AvWsXl0fEx02iXR8uhDsVGhmM9Pse
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