How do i change the volume with a windows keyboard?

[punky_munky]

I've got myself a nice little wireless keyboard with trackpad for my mac mini media centre plan. It's basically a laptop keyboard and I can't figure out how to change the volume in OS X nor can I find a way to reconfigure the keys. Any help?

 

[punky_munky]

Thanks for replying. I'll have a crack at remapping when I get home - from that screenshot though I can't see any way of changing the Function keys. I'd like to use F4 and F5.