Wedding photography advice, night wedding indoors.?

Ok, So I'm a fairly new aspiring photographer, its been a hobby of mine for the last year and half or so...I just got a Nikon D80 a couple months ago. I don't have much experience with Portrait and people photography, as most of my stuff is landscape, nature, and other random things. I'm going to... show more Ok, So I'm a fairly new aspiring photographer, its been a hobby of mine for the last year and half or so...I just got a Nikon D80 a couple months ago.
I don't have much experience with Portrait and people photography, as most of my stuff is landscape, nature, and other random things.

I'm going to my first wedding a week or so, and will actually the photographer of the wedding, since its for a friend.
Her wedding is going to take place at her house and in her backyard. Probably during the the late afternoon where its going to be Night time.

How i should i prepare to shoot pictures that may be in a darker atmosphere? What is a reasonable ISO level where i won't lose quality?
I plan on bringing a tripod, and only have my camera flash. I will be using an 18-55mm VR nikkor lens. I also have a 55-200mm Lens VR, will i need it?

I'm a little nervous and don't want to screw up..so any advice would be awesome.

thanks.
Update: I'm considering getting a backdrop studio set up. with two umbrella lights to bring her house for a photo shoot after the wedding..does this sound like a good idea? this for the lights: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350180533744&_trksid=p3907.m32&_trkparms=tab%3DWatching this for... show more I'm considering getting a backdrop studio set up. with two umbrella lights to bring her house for a photo shoot after the wedding..does this sound like a good idea?

this for the lights:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=350180533744&_trksid=p3907.m32&_trkparms=tab%3DWatching

this for the backdrop:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=160322184869&_trksid=p3907.m32&_trkparms=tab%3DWatching

are these good prices? I have been looking on ebay a lot and they seem like a cheap price compared to others.
Update 2: and wow sorry about the spelling errors there, i rushed through when writing the question
Update 3: Yea i agree that she needed a professional, i told her many times I'm not a pro and don't have all the equipment. It was either me, or one of her other friends who didn't have a camera and would have needed to use mine. I think I"m her best option since there low on money, and photographers tend... show more Yea i agree that she needed a professional, i told her many times I'm not a pro and don't have all the equipment. It was either me, or one of her other friends who didn't have a camera and would have needed to use mine.
I think I"m her best option since there low on money, and photographers tend to be expensive. I'm no pro, but I'm free..for now. And I know i will do a better job than just some random guest with a camera
Update 4: any additional information on what ISO i should be set at?
I was thinking about 300, or is that to high?
14 answers 14