New imac and power pc G5 is there any way i can connect the two

We are currently in a situation where we have just purchased new intel imacs running 10.7 but still need to use software on a pre intel power mac g5 running 10.4, (specifically quarkxpress 6.5) this is a temporary thing and in a few months we can retire this program and the computer completely, at present it looks as if we will have to keep both machines running but its not that practical having two computers, two monitors, and two lots of mice and keyboards on one desk.

their currently seems to be no way to connect the g5 to the iMac and use the iMac as a monitor (thanks to thunderbolt) and I've tried logging into the old mac via vnc and log me in but these programs seem to suffer screen tearing and lag and are not that practical for design work.

so their's my issue am I stuck with two sets of equipment on my desk or is there a way round this

thanks in advance