Can't tell much about the wiring, sorry.
Ruud, your schematics are a bit _big_, and it's easy to lose the overview.
But now some more (hopefully constructive) comments:
That VT82C42 heyboard\mouse controller seems to be very exotic.
For instance,
PIC18F452 has a parallel slave port, but PIC coding ain't fun.
BTW: I would put 100 Ohm resistors between the PS\2 connectors and the chip, and add protection diodes to the chip.
DS12885 real time clock is a bit "outdated", and the bus interface isn't a nice one.
Try
DS1511Y instead (5V, narrow DIP28). //DS1511W is 3.3V, take care.
To me the 29F010 EEPROM looks a bit small.
Mouser has Microchip
SST39SF010A, SST39SF020A, SST39SF040: PDIP32, 70ns, 5V.
FTDI has some chips with USB
host functionality.
Vinculum can interface to a USB mouse, but when it comes to handling USB sticks it can only open one file at a time.
We were not pleased with the Vinculum II IDE, and of course the chip is completely different from the Vinculum.
Maybe you should take a look at the FT313.
For Ethernet, take a look at the
ENC28J60 section of Daryl Rictor's homepage.
Microchip
ENC28J60 does 10BASE-T, PHY already on_chip, the SPI is sort of a drawback.
When using the shift register of a 6522 and a 74164, something could be improvised. BTW: 74LVC245 makes a neat 5V\3.3V level translator.
But one needs to be a bit paranoid about the SCK to rising edge /CS timing (when doing something wrong there, all registers on the chip could be read/written except the PHY registers).
//Another option to "6522 + 74164" would be using
65SPI for implementing the SPI.