What kind of screws can be used for securing Dimension 4400 expansion cards?

Hello all,

After sitting in storage for almost 10 years, my dad has recently dug out my Dell Dimension 4400, my first ever personal computer, which has been sitting in storage since about March/April 2008. I decided to do my own work on it, like swapping out the 20GB HDD with a 250GB HDD, added in a 10/100/1000Mbit Ethernet card, and expanded the RAM from 128MB to 2GB.

Within the last couple of weeks, I've ran into issues. I managed to break the tab that keeps the securing lever down, and broke a tab that keeps the AGP video card secured. It's so bad that I have to make sure to plug in the VGA cord into the PNY GeForce FX 5200 before closing the case, otherwise I risk dislodging the card from its AGP 4x socket.

I thought I had some screws used for securing expansion cards to the back plate, but they didn't fit. Is there any information as to what screws are compatible with securing expansion cards to the backplate?