Its all good
yup you got in the right path man, new hardware is the key here. Now if you move your current distro to your new PC, I would be only concerned about the kernel.
If you could get a some kernel running enough to boot up, I would compile then a custom kernel foro your new hardware; here is how i can see it working:
In old working compu...
Compile a kernel for your new hardware (or install a kernel image)
Move you HDD to new PC
Try to boot, with some luck all will work enough to be able to set your new configurations (X-server, paths etc..)
What I would be worried the most is the logical position of your HDD.
I.E. If your current linux is running in hdb1, in the new PC it should be logically in the same place.
And you would only have to install or tune up your grub/LILO
Evaluate what solution will take less efford for reliable results.