dsl to cable problem

Okay so heres the deal. I had sympatico dsl service for a long time. I had it set up on my two PCs using a linksys wired router. Now that I switched to a cable connection I cant get these computers to connect to the net. I can get them to work individually if i connect them directly to the cable modem but the second I put the router in the equation they cant connect. So my question is this, what settings do i have to change on my router or on windows to get my computers connected again. I never knew the switch from dsl to cable would be so complicated.

Go into the routers config after it is plugged into the cable modem via the wan port. Choose clone mac address. then try again.

wait a sec, the cable modem shoudl go into the wan slot on the router?
seriously, when it comes to networking im a pretty big newb

WAN = Wide area network.. that's where the internet goes.

After that, you just need to go into the router's configuration in the WAN/Internet section and change it to be a direct connection using DHCP to retrieve an IP address.

sorry ive been away for a bit.
Well it seems to work, except now each computer connects but it randomly diconnects, then reconnnects again. This normally would not be noticable cus it does it so quickly but when im on msn it logs off then logs back on, very annoying.

how do i solve these random disconnects.
Could someone tell me what the settings on my router should, like every field and option???

For starters shoudl i be using "obtain IP automatically" or "static IP"

Use Obtail IP Automatically, unless your ISP told you to use a certain IP address.

As for the random disconnects, do they happen if you remove the router, and just plug your computer into the cable modem? If so, then it's the router's fault, if not, then it's something wrong with your connection, try calling your ISP and get them to do a line check.

they have done a line check, and when I connect directly to the modem there are no diconnects.
Thats why i feel it must be the modem, but i know it works, it worked with my dsl a little while ago , so i think it must be the settings