@Irishk,
I suggest you start by looking at these 40 inch HDTV displays in person. Check the following (or current similar) models for around $700 - $1200. the newer models are more likely to have the 120 HZ refresh rate (better for sports and following action in movies).
I'd advise against getting a TV through mail order. I'm a big fan of buying small electronics through mail-order. However, with large displays it's costly and iffy though I know some people that are highly satisfied. I would advise anyone interested to read Amazon consumer blog about getting HDTV and large TV display delivered. There's enough negatives to scare me off.
Samsung . UN40C6300, 40" HDTV - following specs: 1080p / 120Hz / LED-LCD HDTV
$1099
My purchase on 4/15/10 was a 46 in Samsung UN
46C6300 for $1260. the smaller model is identical. the specs are good and is only 1.25 inches thick. I think mine draws less than 100 watts. as opposed to non LED HDTV that draw 300 wt or more.
Sony - BRAVIA KDL40EX700 40" / 1080p / 120Hz / LED-LCD HDTV
$1260
Panasonic - VIERA 42" Class / 1080p / 600Hz / Plasma HDTV
$670
As a professional photographer and former computer professional, my preferences come from first-hand experience. Also, FWIW, I have a sister who worked as studio engineer for MTV who added her input to my recent purchase. I trust her 15 yrs pro experience with high resolution displays even more than my own. She swears by Sony, Samsung and Panasonic (plasma).
That being said, I suggest you can narrow down your search to Samsung, Sony and Panasonic. House brands at Best Buy like Dynex are not worthwhile as their performance and longevity is quite suspect.
Yes, there are several other attractive options that have reasonable prices and decent looking displays (Sharp Aquos etc.), but they haven't the trouble-free quality of those first three. Statistics and real-life experiences don't lie.
You can purchase and get a cost-effective no interest-loan without using Amazon. The delivery options for a delivery of a large display item are not attractive to me. Fragility, Insurance and timing of delivery is much more costly and less attractive then let's say going to Best Buy and self-pickup or having them deliver, as an example. Also, freight charges for oversize packages reflects in the big hassle and overall cost. Your savings overall is minimized.
That's my quick take on it. If you see a model before you buy, feel free to bounce the details off of me. I'll give you my opinion-rating and tell you if there's a better or equivalent model and also let you know if the deal is good too.