Question about PC3200 RAM

[DEATH eVADER]

My system can hold a maximum of 2Gb of PC3200 RAM. I initially had a total of 1GB (2 sticks), but have just recently bought 1GB from the same retailer. However the RAM that I just bought is not from the same manufacturer. Not only that but it is described as "DDR 1Gb PC3200 400MHz UDIMM" and on the other side it says DDR2.

In short

Will I be able to use RAM from two different manufacturers in the same computer?
What is UDIMM?
Are all PC3200's DDR2?

 

[JellyWorld]

There's no way you can mix DDR2 with DDR, and PC3200s come in both DDR and DDR2.

 

[Asus]

You want PC3200 DDR.
DDR memory has 184pins.
DDR2 memory has 240pins. DDR2 will not work for you.

UDIMM probably stands for Unbuffered DIMM and both DDR and DDR2 in desktop systems is Unbuffered.

What board and CPU do you have? Or do you know if your board supports Dual channel memory or just Single channel memory?