I think your only option for c64 emulation using ppc is frodo. It should be ok, but wont be perfect. A 25mhz 68040/160mhz 603e card isnt a great purchase in my opinion (I say this because I had one). Id have preferred an '060 card. The best thing about the bppc was the connector that I connected my grex to (ergo the ability to add a video card and sound card).
With aga though it adds pretty much nothing and apart from a few bits and pieces you'd be better off with a standard '040 card even (the '040 side on the card youve mentioned is the weakest '040 card available).
I hope you enjoy your purchase, but I warn you, be prepared to be disappointed. For me it felt like a huge waste of money and effort
Maybe but there is one thing I discovered in my experience with Amiga hardware and it is this:
1) Every time you invest your money on an Amiga hardware and sell it, you always get your money back and more sum.
2) This card is 175 Mhz PPC actually and can be upgraded to 300 Mhz
3) I can have 256 MB of RAM now with this card
4) The 040 being 25 Mhz is still going to give a big boost to my current speed of my Amiga 1200 where it stands now
5) The value of my Amiga 1200 with the PPC card and a USB Sub now jacked up dramatically.
It is still better that card I am getting than the current setting I have now and because of this card I can upgrade my AGA to BVision PPC card where as a normal 68k card will not be able to give me this privilege. Worse case scenario...at least I can try out AmigaOS 4.1 even if it is going to be slow...giving me an idea and feel of this OS and software without buying a whole NEW COMPUTER and spend 3k for it...with this..I can OS 4.1 classic version and experience what the big boys are experiencing in their modern PPC computers and still use it on a desktop case A1200.