need help with video card upgrade

Your L-series machine has the Intel AGP graphics integrated directly onto the motherboard, hence your system has no AGP slot. Consequently, you must purchase a PCI video card in order to upgrade. It sounds like this game has pretty minimal video card requirements, so you should be fine with a modestly priced card. I would recommend something like a Radeon 9000 or GeforceFX 5200. Both of these cards also come in AGP versions, so be sure you get a PCI model! You can try local brick'n'mortar stores like CompUSA or Best Buy, or you can get one online. Here's a nice card at a good price (including free shipping) at a very reputable online reseller, Allstarshop.com:

http://www.allstarshop.com/shop/product.asp?dept%5Fid=341&pid=8299&sid=Q909KWG3QL1W9PW39VRDLJUCLACL1GFA

Once you get the card of your choice, just install it per the instructions that come with it. You'll need to disable the onboard Intel AGP graphics, so that your PC uses the new PCI card as the primary display device. The link at the top of the Dimension Video forum page entitled "FAQ - ONBOARD VIDEO ENABLE/DISABLE"  provides instructions on how to do this. Just scroll down the page untill you see the instructions for "Lxxx, 2100".

Hope this helps....