You just installed your new network card. All the drivers are installed, all the correct LED’s glow, the stars are in alignment, and the thing STILL will not work. Symptoms include corrupted files when transfering, not being able to browse your network,  and sometimes dropped packets when you run a PING.  What you may be experiencing is an IRQ conflict. Your computer ‘should’ be able to share IRQ’s between cards but often, network cards like their own IRQ.

Since IRQ sharing is not considered a ‘conflict’, your computer will not raise any red flags (or yellow exclamation marks!). No errors will occur, but your network card will still not work.

In comes a handy system utility inside windows called MSINFO, or rather, MSINFO32.

From the START menu, select run and type in MSINFO32.exe and click OK

Open the “Hardware Resources” tree and then select the “Conflicts/Sharing” folder. If your NIC appears here, your NIC is sharing an IRQ! NOTE: if it is only sharing an IRQ with "PCI IRQ Steering" it's OK.  IRQ steering is not a real device.

The best way to change the IRQ your NIC has is to place the NIC in another slot. If you do not have another slot, you may have to swap your cards around to find a combination that works. Many cards these days do not mind sharing IRQ’s, but NIC’s are often not one of them.

According to Microsoft (article here), placing your NIC in PCI slot 1 is bad news.  You will probably end up with a NIC sharing an IRQ with your video card.  Symptoms: "Unable to browse network" messages when looking at your network neighborhood.  Read the article for the fixes

Good Luck! (you might need it)