help for virtual lab

Alfisti

hi sirs

i turn to you for many questions and i wonder :
i would like a help and some hands help too
i've to manage a big network : Gwan > voice > switch > lan
All materiel :
Routers : 2800 series
Switch : 3750 , 4500 series

i'm searching to do a virtuel lab on my machine for switches and routers

could you hep

THX