camera set-up for highest resolution???

[Dwig]

... i need the pictures to be the highest possible resolution i can get, since they will be projected onto a 150"+ screen at the actual auction. ...

Before you go any further, you need to contact the auctioneers to find out exactly what type of projector they will be using and in what format the images need to be submitted.

If they are using a digital projector they will likely want images in JPEG format. They won't need anything particularly high resolution. The D90's full resolution images are higher resolution than virtually any digital projection system.

If they are still "old school" and want classic 35mm slides, the D90's images are going to be a bit difficult to use. Few labs offer any digital-to-film services.

 

[Shockey]

Since you don't even know what raw is shoot the pics in Jpeg.
Set all your adjustments to the default settings in your camera except make sure the picture quality is set on the largest best quality jpeg, probably Fine. Make sure the exposure is nice and bright, if you have to brighten it in PP you will lose some of your critical sharpness.
Shoot at 24mm if you have the room, shoot in Aperture priority at F5.6 and ISO 100 or 200 whichever is the lowest setting on your camera, use a tripod or solid rest.
This will give you the sharpest and highest resolution photo your camera is capable. Sharpness of the photo will be as critical as resolution.

 

[djacobox372]

Do you know the resolution of the projector? It's very unlikely that it's capable of projecting more than an 8 megapixel image, in fact it's likely only around two megapixels.

The sony 4k projector, which costs about $40k, is the highest resolution projector that I know of and it's only 8 megapixels.