Router simulator software for windows PC

I am reviewing several router simulator software programs to be used in getting my CCNA, i.e. Sybex Virtual lab, Sybex Virtual Lab Gold Edition and RouterSim CCNA 3.0 standard addition. Are there any other router simulator programs out their which are better, and can be used not only for the CCNA but the CCNP and CCIE also ???? Trying to get the most functionality for my money ???

TKs
Dave