StreamWriter with a lots of async writes per second

Hi guys,

I want you opinion about something. We are investigating something to store a huge amount of information. Basically, we want the following:
- We recieve information via a webpage/request (about 4000 per second!).
- This requests needs to be logged in a file
- The file will be once an hour uploaded into our data warehouse. The data warehouse only accepts a file, so we can't write it directly into the database.

The only thing the webpage does, is to write the querystring into the file. To do this (I believe) I have two options:
1. Create a new StreamWriter for each call and write the line.
2. Create a singleton StreamWriter that will be open constantly.

I think that option 2 is the best to do this. What is your opinion about this?

Offcourse I just could try it, but I want your opinion first before I do any coding..

Are there any other options to write the data to the file I'm not aware of?