Problem description: My old hard drive was dying so I bought a new one and installed Windows 7 on it. The old hard drive was running Windows XP. I have a DI-624 router that ran fine on XP. On Windows 7, I have no network access and get the error "local area connection" doesn't have a valid IP configuration. When I plug in my old dying hard drive and boot through XP, everything is fine and the connection works normally. Also, my laptop can connect to wireless fine throughout all of this.

Attempted fixes:
-checked to make sure I have the newest firmware of the router (I do)
-tried installing new drivers for the router
-disable and re-enable LAN, both before and after power cycling the router and modem
-tried a suggested fix of manually assigning a default gateway of 192.168.0.1 (the router's IP address)
-manually assigned IP address (when I do this with the above manual default gateway, I still have no network access but the troubleshoot messages changes from "local area connection doesn't have a valid IP configuration" to "troubleshooting couldn't identify the problem."
-disabled IPv6
-reset TCP/IP, netsock, flushed DNS, etc

Recent changes: It is a fresh install of Windows 7, so it couldn't be from any recent changes. Other than that there are no hardware changes either, but it can't be hardware related anyway since plugging in the Windows XP hard drive lets internet work fine.

So after all that, I got so desperate that I just decided to ORDER a USB wireless adapter. Since my laptop can connect to the router wireless just fine, I figured it would be a stupid but effective workaround to get the desktop to have working internet.

The adapter got here today and when I booted up the desktop for the first time in a while, and surprisingly the wired connection was working fine. It asked me if the network was private, home, etc, I set it as home and it worked fine. Downloaded STUFF, browsed, etc, it asked about Homegroup, I told it no, and it continued working just fine for several hours. I had to reboot for something and of course upon rebooting it was back to the usual error - sees my network as a public network, calls it Unidentified Network, no network access, and the troubleshooting error of:

"Local area connection" doesn't have a valid IP configuration

I tried using the USB wireless adapter and it's giving me a no network access error despite seeing/connecting to my network wirelessly. Honestly, I'd rather just get the wired connection working anyway so I don't mind that the USB wireless adapter didn't work.

I have no idea what else to try at this point other than going back to XP, but I really, really want to avoid that if possible. I know it's not a hardware problem since the wired connection has worked on Windows 7 at random at various points, so there must be some niggling setting that is being overlooked. Any ideas?

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OPERATING system: New hard drive has Windows 7 Enterprise 32-bit. Old hard drive was Windows XP.

System specs:The router is a DI-624, the network adapter is "Realtek PCI GBE Family Controller", the motherboard is a Jetway 848PDC(P)

I have GOOGLED and read the FAQ: Yes, all the google responses for this issue suggest that disabling/re-enabling the LAN or manually setting the default gateway should do the trick, neither of which worked for me

Thanks for any help!