You have not said what your previous O/S was but suspect it was win 7 64bit.
First just installing a win 7 should not have destroyed your recovery software on the hard disk.
These days a hard drive comes with at least two partitions And will be seen as two separate drives "C" and possibly "D". So when the new system went on only "C" would have been formatted.
The recovery software is usually with most manufactures is in a hidden partition for security.
The recovery routine is on your laptop entered by pressing F8 several times after the Dell logo has disappeared in some cases but not in all. I refer you to this Dell web page under method 2
http://support.dell.com/support/topics/global.aspx/support/kcs/document?c=us&l=en&s=gen&docid=DSN_362029&isLegacy=true
As for the operating system you have on now. ref to this web page for all the drivers,particularly under network for your problem.
http://www.dell.com/support/drivers/us/en/19
you will have to decide which hardware you have.
As you are the legal owner of you O/S licence you can apply to dell for a copy of your recovery on disk. You will have to prove you are the registered owner there will be a charge but that depends on Dell.
If you want further help contact me and if I can I will do
If you go for the recovery you will loose all you own data on the "C" drive so backup what you do not want to loose