There are several interesting options for you but you have to be clear on what you want:
1) Have you gone to best buy, Costco.com, etc to check out the dedicated DVD players (not a computer) which have their own LCD screens ? You can get a very nice one for $500 or less in many cases but these only play DVD's on their own built in LCD and are much thinner and lighter than any notebook computer. Examples of quality brands: Toshiba, Panasonic, etc in varying LCD sizes/Costs
2) HP just came out with a brand new model at hpshopping : dv1000 -- it allows you to play DVD's without booting up the computer (or CD's) with controls on the front panel. Also, it has a remote PC card that goes into the PC card slot when not in use. It has a 14" LCD and is a Pentium M (Centrino) notebook 1.2" thick and 5.3 pounds. This may be ideal for you uses except for one thing -- GAMES -- it has integrated graphics (not a dedicated video card) so it will play simple games and do web-surfing, etc but it will not play Doom 3 or any other game requiring a built in dedicated video card chip. This notebook also should fit well between the car seats assuming you mount it on something properly.
3) A full-fledged multimedia computer like the Compaq X1000 or HPZT3000 (I have one of these) has an option for 64mb dedicated graphics (128mb is better but most of those are at or close to $2000), a 15.4" widescreen LCD, etc. These can very easily be purchased for under $1500 after discounts ($100 custom order rebate) but they are wider and heavier than the above -- 6.5 pounds.
Give me more of an idea of what you want. If you really want one device to use in the car and use for wi-fi (web surfing, Microsoft office) then the DV1000 is a decent choice (or similar new Compaq model is somewhat less but doesn't have the built in remote control and some front panel controls).
If you really want a notebook that can play games you would be better off buying a 7" Toshiba Dedicated DVD player (meaning DVD player only -- no computer) with LCD (very small and light) and then get a notebook somewhat larger and with a dedicated video card for games.
Let me know which way you are leaning.
I am looking for an relatively inexpensive, reliable laptop that I can use to surf the web, play games, and have my daughter be able to watch a dvd on trips in the car. Any recommendations on products that would fit this description and what accessories I may need with it? I was hoping this would be a better use of $ instead of the $1500 auto dealers charge for their installed DVD players. Thanks

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