Internet and Network screwing up

[da_head]

Guys i'm in desperate situation. its pretty complex. ok here goes. recently i got a new dlink and i have 2 computers (desktop windows xp pro and laptop windows xp home). i have bell sympatico high speed internet (dsl that uses modem). the desktop is connected to the dlink router with a cable and the laptop recieves the signal wirelessly. sometimes both computers would lose their interent connection at the same time (network signal is excellent). the internet would become exttttttttttttremly slow and like 5 mins later it would be fine again. i have called both my isp and dlink and both seem fine. wat is even stranger is when i don't connect my router to my desktop (which means only laptop has internet), the internet seems perfect. but if i'm correct, the desktop has nothing to with the router rite? the phone line goes into the modem, the modem connects to the router and the router sends out the signal. is it possible that if the desktop has a problem, it ruins the laptops internet connection as well? and strangely periodically when both computers are connected, my network doesn't seem to work even though it says excellent.
can u guys plz help!! (btw i no my explaination is not very clear. if u don't get something, please ask)

 

[Samstoned]

enable any "keep alive" feature in router
reload the nic drivers for pc
make sure you don't have connection provider software running on pc
this will mess up the router
I used to set mine to static ,but that can be a hassle if your isp is updating address's a lot
you can try it may help make sure router has dhcp disabled
set both nics to 100 full duplex or both to auto
one setting will work better than the other
it can be a virus on the pc do you have any firewall setups other than xp default

 

[da_head]

ya i have norton. wat is a nic? my internet connection is PPOE not dynamic or static. my router has always connected enabled. why should i disable dhcp? not that i'm doubting u but i just want to no y.
btw:i tried your suggestion about diabling the dhcp and found that the connection on one computer is excellent and the other one says limited or no network availiability because the network hasn't assigned it some number.
perhaps when i use the dlink to split up my connection, it becomes really weak?

 

[da_head]

Hello someone please help me!!