I am trying to plan out my system and wondering if it is possible to connect a DVR to a wireless router. Here at the details:

I have a two story house, with the office being on the first floor (this is where my computer/modem/wireless router are). It would be very tough to get all of the cameras run to the first floor and so I am hoping to place the DVR on the second floor, however, I don't have any Ethernet run upstairs.

Is there any way to connect my DVR to my network using a wireless connection?

You can buy a device called a "wireless access point" which should do what you want.

Yep