Siemens S7-300 Comms to a PC

Hi All,
I'm stepping into some work with some S7's and I need adapter to communicate. Which is the preferred method? The CP5512 (PCMCIA) or the 6ES7 972-0CB20-0XA0 (USB)? -I understand the CP5512 and uses the PC’s power where the USB needs the processors power to operate so it is limiting.
-Do they both work in a virtual environment? I wanted to use a vmware machine incase it doesn’t play nice with the Rockwell software on my laptop.
-can an OP Panel program be downloaded with both? Or is a serial cable required?

Thanks

What kind of 300 is it? If it's a PNDP variant, You can use ethernet. Many of the panels also have ethernet interface. If not, and if you will use S7 occationally, go for an USB-MPI.

This is an alternative to Siemens:
http://www.ibhsoftec-sps.de/english/Selection_Hardware_S7.htm

Reg.
Kalle