I am thinking of purchasing the Dell Vostro 220 Mini tower. I am thinking of going with the onboard graphics option, but then adding two video cards to it so that I can support 4 discreet displays. I am not a gamer, and will be using the displays for Office apps and generally to multi-task.
First, I will advise not to buy Dell and build your own. If this is not an option, than here is the rest. That PSU is the minimum power supplied to power everything in that mini. It will not support any other GPU modifications what so ever, let alone running two of them. So you have to upgrade the PSU to support the GPU you want to install, thats an absolute, no cutting corners here. The 9400 you are looking at just makes the cut having 300w minimum requirement, anything rated higher will not be compatible with your setup. Secondly, if you want to purchase a more powerful PSU, hope that fits in that mini, than you are limited in space and most importantly, PCI-E x16 slots. Its seems that you are limited to one PCI-E x16, and modern PCI-E cards all require x16 for graphics computing. Always read the card's requirements specs before purchase. You can run one PCI-E x16 card, but not 2. Translation, in order to run 2 cards, you have to have more of these favorable slots on your MOBO, no exceptions. So that will result in upgrading the MOBO as well. Real good reasons why we build, not buy. You are very, very limited here.
I'm retracting my advice. The OP hasn't bought the Vostro yet... DO NOT BUY THAT. It is inadequate for your needs. If you truly require 4 monitor support, buy a computer that can properly support that kind of setup. Since you're not into gaming, you're aiming for the right (i.e. low-end) cards... but that Dell's PSU might not support that extra load.
I don't think I am up to the task of building my own PC. However, I am also looking at the Vostro 420, which has a bigger (350W) power supply. I remember posting about the Vostro 420 earlier and from the feedback that I received I thought this could be done.
Here are the specs that I am looking at:
Intel® G45 Express Chipset
Intel® Core™ 2 Duo E8400 (3.0GHz, 6M, L2Cache, 1333FSB)
Windows 7 Pro - 32-bit
250GB Serial ATA Hard Drive (7200RPM) w/DataBurst Cache™
3GB DDR2 SDRAM 800MHZ - 1x2GB 1x1GB
Single Drive: 16X (DVD+/-RW) Burner Drive
512MB ATI Radeon™ HD 4350 - Dual Monitor - On the PCIe x1 slot
Integrated 5.1 Channel Audio (No separate Audio Card)
There are two free PCIe x1 slots on this computer and I know that HIS makes a low-profile PCIe x1 graphics card with the same ATI HD 4350 chipset. It's available here: