56Whr Lithium Ion Battery (6 cell) - How long does it last?

Hello, I'm Kazu, I'm 14 years old, and was just customizing a laptop to buy. But for the battery part, I'd like to know how long a '56Whr Lithium Ion Battery (6 cell)' battery would last. I'm really hoping that it's at least something like 4 hours, I really hope it's not something like an hour and a half, because a future project I'll be working on requires a lot of time at a time when I'm using the internet. (I'll be going to a wireless cafe because I don't have wireless at home and I can't exactly keep the charger plugged in there, hehe.)
If the battery depends on the other stuff I have on the laptop, here are all of the components:

My Components
SYSTEM COLOR Jet Black edit
PROCESSOR AMD Turion™ 64 X2 Mobile Technology TL-56 (1MB/1.8GHz) edit
OPERATING SYSTEM Genuine Windows Vista® Home Basic Edition edit
MEMORY 2GB Shared Dual Channel DDR2 at 667MHz edit
HARD DRIVE Size: 160GB SATA Hard Drive (5400RPM) edit
INTEGRATED WEBCAM No Webcam Option edit

My Service
WARRANTY AND SERVICE 1Yr In-Home Service, Parts + Labor,24x7 Phone Support edit

ALSO INCLUDED WITH YOUR SYSTEM
DISPLAY Glossy, widescreen 15.4 inch display (1280x800)
VIDEO CARD ATI RADEON® Xpress1270 HyperMemory™
OPTICAL DRIVE CD writer / DVD player (Combo Drive)
WIRELESS NETWORK CARDS Dell Wireless 1490 802.11a/g Mini-Card
BATTERY OPTIONS 56Whr Lithium Ion Battery (6 cell)
SOUND OPTIONS High Definition Audio 2.0
TBU Adobe® Acrobat® Reader 7.08
Label VISTA BASIC STICKER,INSP
DOMS Camera Mod Jet Black color w/o Camera
Network Card Integrated 10/100 Network Card and Modem
Miscellaneous Inspiron 1521
GETTING-STARTED HELP No Dell On Call
DATASAFE ONLINE BACKUP Free 3 GB Online Backup for 1Yr
DIAL-UP INTERNET ACCESS 6 Months America Online Internet Access Included


If someone could help me out with this, I'd be very grateful to them. Thank you!
(P.S, if this is in the wrong forum, I'm very sorry, this looked like the most compatible forum for my problem.)

 

Have a read of this review which is for a Dell with similar CPU and display. That notebook could, under optimum conditions, manage over 6 hours with a 9 cell battery which means 4 hours on a 6 cell. However, if your turn up the brightness, use wireless, etc, that time will drop. I think the 9 cell battery may be a safer choice, or maybe you can get one of each in your order for a reasonable cost (extra batteries are much cheaper to include in the order than to buy later, and you should assume that you will lose 1/4 to 1/3 of capacity over a year).

If you are going to be carrying the notebook a lot then I suggest you consider a 14.1" model. Their smaller size is much easier to carry around (and the smaller display means slightly less power used by the backlight).

John

 

Good choice of gfx if you want to extend the battery life too, not for gaming but it will give you nice 2d/video quality and draw less power than a dedicated chip.

 

Thanks, both of you! Now, I have just 1 more question. How exactly would I get a 9 cell battery? I don't see it in the customization, all I see are System Color, Inspiron 1420, Operating System, Memory, Hard Drive, and Camera. Would I just buy one at Best Buy, or Curcuit(Sp?) City? If so, how much would they cost?

EDIT: Haha, I've been a fool, I just realised now that laptop batteries are stuff you plug into the laptop while using it..to be honest, I thought it was programmed into the laptop. XD Anwyays, thanks very much John and Meaker, all my questions are answered, and I'll take your advice on the 14.1" model, John.

 

It should be listed under primary battery, they slot into the machine but are removable.