Just about everything in the PC architecture has been upgraded -- much better microprocessors, more elaborate OS's, more memory, a much higher bandwidth bus architecture, etc. However, one bit of 1980's era design still sits at the heart of the computer - the BIOS. Sure, manufacturers have agreed to some extensions (particularly plug and play) and motherboard makers add in extensions of their own (e.g. for overclocking) but the basic BIOS architecture and functionality, which sits underneath the OS and gets things started when you flip the "on" switch, is basically unchanged.
A few years ago, Intel proposed a replacement, but ironically only Apple has picked up on the BIOS replacement called EFI. Now, it appears, at least one leading motherboard manufacturer for PC's is putting a toe in the water:
The specification allows for a considerable change in what can be implemented
at this very low level.
EFI is a specification that defines a software interface between an operating
system and platform firmware. EFI is intended as a significantly improved
replacement of the old legacy BIOS firmware interface used by modern PCs....
Graphical menus, standard mouse point-and-click operations,
pre-operating-system application support such as web browsers, mail applications
and media players, will all feature heavily within EFI.