Bridge networks 192.168.0.1 (D-Link DIR-635) and 192.168.1.1 (Zyxel ADSL2+ Router Modem P660HW-D1)?

you should see if you can set the zyxel as a wireless ap instead of router.

The topology isn't all that clear to me:
You said:
Inner network is connected to a D-Link DIR-635 to which both wireless and wired are connected. Only one nettop connects directly to  the Zyxel modem/router using wireless.
There is a Windows 2000 server on the inner 192.168.0.1 network which I sometimes need to access from the nettop using Remote Desktop but I just cannot figure out how to configure the two routers for this to work.
My network is ok (seems ok) except the nettop-server problem.

OK - I'll try to decipher out a topology:

***
Zyxel modem/router with a public IP address on the "outside" WAN internet port
and
Some private range address on the "inside" such as 192.168.1.1
***
D-Link router's "outside" WAN internet port  connected to a Zyxel "inside" LAN port with an "outside" address of something like 192.168.1.2.
and
D-Link LAN address of 192.168.0.1 as you've stated.

***Comments and recommendations:

1) The D-Link and the Zyxel LAN address ranges should *not* be the same.  You'll notice above that I assumed they were not.  Make sure this is the case.

[I will refer to your "inner layer" as the "2nd level" and what you must mean as the "outer layer" (not mentioned) as the "1st level" for the two LANs.  The Zyxel's LAN is at the 1st level as is the D-Links WAN.  The D-Link's LAN is at the 2nd level.]

2) No computer connected into the first level will reach the 2nd level.  Conversely, a computer on the 2nd level can reach computers on the 1st level.  That's because private addresses in a different range will not propagate UP through either of the routers if they meet the standards, unless it matches its WAN range.  Otherwise such packets are dropped.

So, if a router has a private address assigned on its WAN (as your D-Link surely does), then it can accept traffic destined for its LAN if it's identified as the next hop.

See:
http://www.coastal-computers-networks.com/How%20Subnets%20Work%20in%20Practice.pdf

In your case, if you are connecting one computer to the Zyxel then it won't connect to any on the D-Link.

But, if you turn things around it would work:

Put all of the computers on the Zyxel LAN and put that one lone computer on the D-Link LAN.
Since the Zyxel is also a modem, you can't very well exchange the roles of the two routers.

If you do this then the lone computer will be able to see all the computers on the Zyxel but the computers on the Zyxel won't be able to see the computers on the D-Link.  Is that what you want?