Image rating help

I'm building an image rating app and am having some trouble. I have one db, with two tables, "images" and "ratings".

images Fields - imgid, imgtitle, imglink
ratings Fields - rateid, imgid, imgtitle, imgrating, visitorip, ratedate

The image are shown in random order (using ADO), so the sql is:

sql= "select imgid, imgtitle, imglink from images order by imgid desc"
rs.Open sql, cn, 3, adCmdText

Dim intRnd
Randomize Timer
intRnd = (Int(RND * rs.RecordCount))
rs.Move intRnd

The user rates the image, and then submits a form, which brings up another page, with a new random image.

Although this gives me a random image every time, sometimes the images are repeated. Now how do I make sure that a user gets a different random image every time?

In the ratings, the sql inserts the IP of the user who rated the image. Should I use that or cookies? If I use the ip method, how do I interact with the two tables?

Another thing. Once an image is displayed, how do I check the ratings table to find out if the image has been rated before, and what the average rating is, and display that result?

I am using Access 2000, and i've already made a query that joins all the results:

SELECT images.imgid, images.imgtitle, images.imglink, ratings.rateid, ratings.imgip, ratings.imgrating
FROM images INNER JOIN ratings ON images.imgid = ratings.imgid;

From here, how do I go??