Netgear WGR614 v5 wireless router just won't work

[#1]

A friend has given me this wireless router, (are alarm bells ringing yet?! ) which he assures me works.
Following the step-by-step instructions, starting with a complete hardware reset by pressing the button on the back of the router, then powering it down, connecting everything, and powering back up in the correct order, I cannot get the router set-up page in my browser. It doesn't matter whether I use www.routerlogin.net or 192.168.1.1 - my browser can't see it, or anything else. All the correct lights are on etc. I can't ping the router.

However, if I do things in the wrong order, I can get further...
If I connect the router to my PC, but don't connect the router to the DSL modem, I can ping the router! Also, I can get the router set-up page in my browser! However, the first thing it asks me to do is connect my internet, because it can't find it. I connect the DSL modem, let it find it, and once it tries to configure it the browser can't see the router or anything else, and I suddenly can't ping the router either.

It seems that the router does work (i.e. it's not dead or faulty) but it loses connect to the PC shortly after the broadband modem is connected to it.
What am I doing wrong?
Any help gratefully appreciated. I've tried the trouble shooting and FAQ on the Netgear website and got no where. In fact, if I hadn't have thought to try pinging the router without the modem attached (not suggested by Netgear!) I wouldn't even have got this far.
(The DSL modem connecting to plusnet is the "free" D-link DSL 320B)
Connecting the modem directly to the PC gets the internet fine. When the modem is connected into the PC, the PC's IP address is 87.something as it should be, and when connected into the router it becomes 192.168.1.2 (as I believe it should be).
IP address and DNS server obtained automatically, DHCP enabled.
Any ideas?
Cheers,
David.

[#2]

Make sure that it's not operating in 'bridge' mode.
Not sure of the exact naming, but I do believe that we have one of these in the office, so I'll try and have a peek tomorrow.
B.

[#3]

How would I check that?
It's not a "bridged" connection in XP.
Cheers,
David.

[#4]

Can we assume you are connecting with a network cable and not wirelessly? According to the <a href="http://kb.netgear.com/app/products/model/a_id/2587">manual</a>, the default IP address is 192.168.0.1 - have you tried that? If the router is managing DHCP then it should assign an IP address to the PC in the same range i.e. 192.168.0.x.

[#5]

Yes, wired.
The manual is wrong - 192.168.0.1 doesn't work at all (though I've tried both 0.1 and 1.1 extensively) - 192.168.1.1 is printed on the router itself, and is the one that works - until I plug the broadband modem in!
How can a modem interfere with a router to stop them both working?
Cheers,
David.

[#6]

Actually, that was an obvious question, and the obvious answer was the correct one: they both grab the same IP address (by default).
I'll go away and read the manuals, change one of them, and see if that helps.
(if I'm about to break something, please warn me now! )
Cheers,
David.

[#7]

I don't believe this 

I changed the router IP address to .7.1 as suggested here...
http://forums.cnet.com/5208-7589_102-0.html?threadID=221209
...and can now access the router, on this IP address, with the modem plugged in.

...but I can't get on the net, and can't even ping the modem itself.
If the plusnet log-in details were incorrect (because it's not obvious which of the boxes, if any, to put the username and password into - I think I've tried all combinations!), would that stop me from pinging the modem?!
Cheers,
David.

[#8]

I've returned to this problem after a little break (!). I've spent another night trying to make things work, but failed. Tonight, having got all the correct passwords, I tried changing the D-link modem's IP address, but doesn't work unless you switch its DHCP server off - and after that, I was lost anyway. The Netgear router recognised a static IP address, and demanded all information manually - but wouldn't accept an IP address of 87.112.x.x and a gateway of 192.168.1.1 because they were on different subnets. But that's what seems to be used.
D-link modem + Netgear router. How on earth can they be made to work together?
I've done lots of searching, and the issue of bridging and/or mac spoofing comes up, because the D-link uses the 192.168.x.x subnet, but passes through the ISP provided IP address of 87.112.x.x which (I've read - and it seems) confuses the router.
Is there a solution to this? Or do I throw the hole lot in the bin and buy an integrated ADSL modem+wireless router?
Cheers,
David.