If you're going to wall mount the new set don't pay for the overpriced mounts found at the stores.
Monoprice has the best pricing on wall mounts and I can vouch for the quality. They are every bit as strong as anything you can buy in the store. Here is the link on their website to the mounts.
http://www.monoprice.com/products/subdepartment.asp?c_id=109&cp_id=10828
I have my 47" LCD hanging on the product ID# 3004 and a couple of my other tv's on the product ID# 3003. Yes the prices are a fraction of what you would pay for one in the stores, but the quality is top notch (just make sure you mount them into studs). I would recommend picking one of these up right now. They are in stock and it might not last long. Last year they sold out at Christmas and didn't get anymore in for several weeks.
Also, don't be fooled into paying a ton of money for an HDMI cable (sounds like you will need one if you are getting a blue-ray player). HDMI cables transmit a digital signal, not an analog one. What used to hold true for signal degradation with analog signals won't affect your digital signal. Again, Monoprice has amazing prices on HDMI cables.
I have three LCD HDTV's in my house, a 47" Vizio, a 32" Olevia, and a 27" Olevia. I chose LCD because of the location of my TV's, I didn't want any glare from windows to affect my tv watching. There were several other things that factored into my decision to purchase LCD, but this was a big one.
I researched the hell out of TV's last year and can probably answer a lot of the questions you may have. Plasma's, LCD's, and DLP's all have their pros and cons. Ultimately, you will need to evaluate your situation and decide what works best for you and within your budget. Some of the brothers here have provided some great links to start some of the research. I recommend you decide on the type you want (LCD, plasma, or DLP) and then start looking into the various models.
Let me know if you have any questions that are stumping you about these various technologies, I will do my best to answer them.