You should consider spending the extra $150 and get a computer with an i7.  The laptop I bought in 2009 is now $950, and it has

-i7 1.6GHz/~3GHz with powerboost
-nvidia geforce gt 240m
-4gb ram
-500gb seagate hdd at 5400rpm (crap really )

I know you said $800, but going the extra $150 may be worth it.

It isn't better by a longshot, the 240m has a higher clock speed (easily overclockable, but still), and similar everything else.  The 420m has more cuda cores, that seems to be about it.  I can run 4 1080p videos at the same time with 3286x1080 as my resolution; it seems very powerful to me.  I don't know what more you can really ask for out of a graphics card.

Also, I still say you should push for the i7 or at least an i5.  But that's just me.

one thing wrong with that:
its hp. I have herd soooooo many bad things about hp its not even funny.

Ok, my theoretical budget is now up to $1000. This is because I revisited on how much I can get out of my current computer with everything bundled with it, and I can get a lot more than what I thought I could previously.
and with a $1000 budget.. I shall pronounce my eyes are all for this beast here: http://www.newegg.com/Product/Product.aspx?Item=N82E16834114903

yeah, and plus i herd someone on the irc say that they went through like 2 hp's in a year and they switched to toshiba and said they would NEVER go back again.

the new laptop I have my eye set upon right now: http://www.newegg.com/Product/Product.aspx?Item=N82E16834114903
she's a beauty and a beast

EDIT: YIKES!!!!!!!! look at all the software there is installed on this thing X_X:

Adobe Acrobat Reader, Google Toolbar, Toshiba Supervisor Password Utility, Sun Java 2 Runtime Environment, Skype, QuickBooks (Trial), Toshiba Assist, Toshiba Recovery DiskCreator, Toshiba PC Health Monitor, NetZero Internet Service, Microsoft Internet Explorer 8.0, Toshiba Eco Utility, Toshiba ReelTime, Toshiba Bulletin Board, Microsoft Windows Live Essentials, Toshiba Media Controller, Microsoft Silverlight, Norton Internet Security 2010 (30 days trial), Toshiba Disc Creator, Toshiba Value Added Package, Face Recognition software, Toshiba DVD Player, Microsoft Works 9.0, Microsoft Office 2007 Home and Student Edition (60 days trial), WildTangent Orb Games Console, Microsoft Windows Media Player 12, Toshiba Service Station, Toshiba Hardware Setup Utility, Toshiba Web Camera Application, Toshiba Online Backup (30 days trial)

edit 2: theoretical budget now on $1020 (this is getting more realistic too)

ah yeah, dont worry. I would NEVER go with a dell. Those things are just not good as far as I know.

ah.. well, right now ive decided I want my laptop as soon as I can get it, and by waiting for xmas, im only missing out on $250. So, which means my near future laptop will be this one: http://www.newegg.com/Product/Product.aspx?Item=N82E16834115860

edit: I do want the laptop i posted ^ but I'm not sure if its good or not.. It is a very new laptop and I kinda wish i could find out some reviews on it. So far from what I've found it seems ok.. but you can never tell :S

edit 2: my budget is now at $800. I think that if I can't find a better laptop than that, then ill just go with that one.. I wanna see though if I can find one with a better GPU

edit 3: my laptop is now set to be this one because it has a slightly better CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16834115857

Interesting sites. I am amazed at how quick the CPU in my computer went low in the list. I got an i7 at 2.80 GHz

I own a 2008 Dell Latitude D830. It has a 15.4" LCD panel with 1920x1200 resolution with a discrete NVidia graphics card. Its casing is very robust! It is awesome!

I don't care for the new Dell laptops too much. Dell went cheap with the new designs.

Yeah, I'm using a D820, basically an older revision of the 830. My school got some newer latitudes and they seemed really flimsy.