Dao, I got the LG Philips screen on my replacement laptop. Obviously I was delighted, as the LG Philips screen is widely regarded as being the best. A week later, it developed a dead subpixel (red AND dead!!), which I was not so happy about, but Dell said they don't consider a screen defective unless there are more than 5 bad pixels. At least it is up near the top left corner where it is not too noticeable. The screen is pretty good, though not exactly perfect as it has a pinkish tint on the left hand side, and a dark patch at the top just uner the right hand catch.
I originally requested a screen replacement because the Samsung SEC3155 screen had rather uneven backlighting. In retrospect it wasn't that bad, and I should have just stuck with it. The replacement was the older SEC5777 type, and I didn't realise how awful it was until the service engineer had left. It seems that the engineers will usually bring a refurbished screen. I guess it just depends on how many refurbs they have kicking around as to whether you get a new screen or not. Anyway, after a couple more crappy screens, and a lot of phone calls, I managed to get a manager to authorise a complete system replacement.
As for the DVD burner, the first one I had was the Philips, and as you say, it's like a mini-earthquake. The replacement laptop had a Sony drive which didn't shake but had an incredibly annoying whine. I managed to get Dell to swap it for an NEC 6650A, which still has a bit of rumble but is definitely the best drive by far.
The replacement laptop was new system, straight off the production line the same as if it was ordered from scratch. I was able to keep the old laptop until the new one arrived. I also swapped over the hard drives so that I didn't have to start from scratch. If you do this, you need to change the Windows XP product ID to match the sticker underneath the laptop. You can find instructions on the web describing how to do this.
Hope that helps!