Hi, I would like to buy a power mac G4 quicksilver and install the latest hardware i.e. i5, SSD etc., is this possible?

Intel i5 processor upgrade? No way, no how with the OEM PPC board.

The "Latest" hardware that can be used with the original G4 motherboard is imited to used 7445/7447/7448 3rd party processor upgrades (all obsolete), PCI expansion, AGP graphics (only used as all are obsolete), new IDE drives (capacity support dependant on model year) and PC133 memory.

SATA and SSD can be used, but only with PCI SATA controllers or the specially configured IDE modded SSD from OWC.

PCI controllers will get you about SATA 1 data rates. The adapted SSD on IDE won't get beyond 60 MB/s.

You could use the case and put a mini ITX or micro ATX board in to support the i5. Of course you could then run Windows 7. If you want to run OS X, discussion ends here and begins your use of Google and searching for "x86" and "Hackintosh".