30in IPS panel monitors

Yes, that HP LP series is an S-IPS panel.
Check out the thread at the [H] for more info if you wish, first hand reviews and such.

Personally, Dell's return policy is very nice, no questions asked sorta thing. They want the service tag and that's it. I'd go with the Dell just for peace of mind, considering the monitors are virtually just the same.

However, if you look @ Dell Outlet, there are still a few 3007WFP's going for $700, which is what a lot of people are getting right now.

Is the 3007WFP IPS?

I just looked on the outlet. Those are cheap. Unless they arn't IPS I will probably go with those.

What are the main differences between the 3007 and 3008? Is it just the display ports?

Both are S-IPS panels, and there are two main differences.
First, the 3008wfp has a scaler, meaning if you were to hook up a XBox360/PS3/etc to the monitor, the scaler would resize the resolution to native (2650x1600) instead of 720p/1080p.
Secondly, the addition of a DisplayPort and a few other ports.

If you can live with pixel mapped resolutions for other input devices, or you're just using the monitor for a PC only, go with the 3007. There's virtually no difference in the quality (different DCR, but turn DCR off anyway, since it mucks with colours anyway)