Get more memory.   Find and download vista drivers for any hardware/softeware and updates.  Do a clean install over an upgrade for better results people are finding out.  Be prepared to have some issues.  Since you did not state if you upgraded the integrated video chip you have now on that system, it would be wise to get a dedicated PCI slot card.

 

http://www.newegg.com/Product/Product.asp?Item=N82E16814161017  X1300 1X PCI-Express card. The best you can get, but also expensive, and low end performance..Hypermemory on the this 1x pci-express version shares the system memory - if you only have 512 system the card will only give you 256 for the GPU. If you have 1 GB system it does show the full amount of 512 for the card - although it is still shared memory. Only the 128 onboard is dedicated to the GPU, and it's only 64-bit hardware I/O

http://www.newegg.com/Product/Product.asp?Item=N82E16814143058  PCI 6200 card


http://www.bestbuy.com/site/olspage.jsp?skuId=7638292&type=product&id=1130987962366  6200 PCI slot card - Expensive, for low end game settings.

 

How to disable your integrated video chip as posted by the Moderator

2200, 2300, 2350, 2400, 3000, 3100, E310, B110/1100

* Right click the My Computer icon
* Click Properties
* Click the Hardware tab and/or the Device Manager button
* Open the Display Adaptors. You should see the Intel video card
* Double click the listing for Intel whatever
* At the bottom under "Device Usage", click the down arrow and change this to "Do not use this device, disable"
* Click OK- Apply- OK
* Close all boxes when done
* Click Start- Turn Off Computer- Restart
* Press F2 at the blue Dell logo screen
* Down arrow to either:
Onboard Devices- Primary Video
Primary Video
Integrated Devices- Primary Video Controller
* Change yours to AUTO or PCI (whatever is listed)
* Press ESC several times to Exit and Save your changes
* As the system starts to restart, power the system off
* Open the case cover and add the PCI video card
* Connect the monitor to the added PCI video card
* Power on your computer
* Let the computer boot up and load the drivers off of the CD provided with the card