While I do not dispute the beauty of the picture on these displays, I do dispute their usefulness on a PC...
From the above linked page:
The new Apple Cinema HD Display, like Apple?s other flat-panel displays, is designed to work with your Power Mac G4?s digital graphics interface. Attach it to your Power Mac G4 using the quick-latch Apple Display Connector (ADC) at the end of the single cable, and you?re ready to rock. There are no controls to adjust ? the all-digital signal between your Mac and your display delivers pristine image quality. The ADC cable carries power, USB and digital graphics, and a two-port, self-powered USB hub makes it easy to attach your desktop peripherals.
I have put in bold the pertinant part. There is NO way for you to change settings of this display on a PC.
Now, to add my other two cents.
If you want you could "upgrade" a couple hard drives for me...
Seriously, at this point I see no compelling reason for you to upgrade. You have a good setup as it is. As has been mentioned, if you have to ask, than nothing needs upgrading. Also, as an aside, you mention there always being something new. That, unfortunately, is always the case and always will be. The moment something is on the retail shelves it is nearly obsolete (okay, that is a little extreme) Heck, I just upgraded my GF2 for a GF4 Ti4200 (I didn't need too. I got a good deal, and it's an MSI and matches my MSI motherboard

) and people are already telling me how I have "old" technology and should upgrade. For what I do a Ti4200 is more than adequate.