Two quick things to try first
Go here Realtek
download this driver "Win7 and WinServer 2008 R2 Driver 7.031 2010/11/22 608k" to a folder of your choice on your computer and extract it.
Open device manager and force a driver update. Expand network adapter, right click Realtek adapter and choose update driver software, then Browse, then let me pick, then have disk, then browse to folder where you put the extracted drivers.
Second open the services console
type services.msc into the search box and hit enter
look for either of these two things bonjour service, if present double click it set the startup type to disabled and stop it
a strange ID string that looks something like this
same thing if there double click, set startup type to disable and stop it.
Reboot and see if that helps.
Additionally you may want to check here for your Broadcom NetXtreme 57xx Gigabit Controller for a newer driver than the one you are currently using (7/14/2009) and here for your Intel WiFi Link 5100 AGN wireless adapter (6/11/2009). There are almost certainly newer drivers available which should be updated as discussed in that same post in this thread.
I've been pulling my hair out for 2 days trying to find out why both wired and wireless connections are suddenly NOT working on my laptop. Not a router issue as all other computers in the home are working fine. Then I starting messing with winsocks and all sorts of other fixes found online. When I did an ipconfig there was no default gateway showing up. I even went out and bought another wireless card thinking I could bypass the non-working hardware. No luck. FINALLY, the solution was embarassingly simply. I uninstalled the security suite (in my case Webroot Security Essentials), rebooted, and everything worked PERFECTLY. I reinstalled the security and still works great again. After further reading online I discovered that this is not uncommon. So before anyone drives themselves batty, try uninstalling all security software and try again. You might be very pleasantly surprised.