So I haven't used my Beta Carbon for a while, and got to thinking there is a nice phat 5gb microdrive in there, which would come in handy in my soon to arrive Canon EOS350D....

I haven't pulled apart the Carbon yet, and since it's a beta unit, I guess it will also have the ST1 drive in it that will work in a camera?
I've been reading various forums where people cannot get the newer (Carbon ST1 drives) working in a camera... also there have been discussions on the (lack of) speed of these drives..

Anyone tried this, what the performance of the drive like?

I think you should first ask the question of whether you want to trust your photos to a 5GB microdrive. Given the relative reliability of microdrives to flash and the price of 1GB compact flash nowadays I would far prefer to use two 1GB CF cards than a 5GB microdrive.

In fact, even if someone gave me a 5GB microdrive for free, I still wouldn't use it in my camera.

To answer you actual question, your couple of years old microdrive is likely to be quite a bit slower than a decent speed CF card. Even the recent microdrives are slower than CF:

http://www.robgalbraith.com/bins/multi_page.asp?cid=6007-7699

Do you actually need 5GB card ? Unless you are going to be shooting RAW+JPEG all of the time and shooting many hundreds of photos a day you won't need 5GB.

True... well I guess it's cause the purchase of the EOS350D with the Canon 17-85mm lens, extra battery and case kinda emptied my bank account, so was looking for something to keep me going till I could afford fast flash..

I was contemplating selling my spare mk2a to fund this.... but nahhhh....

It should work fine, but as everyone says, get yourself a fast CF card asap. It'll be faster and more reliable. The XT really takes advantage of the fast cards. Check Rob Galbraith's cf database and buy whatever offers a good price/performance ratio. SD Extreme II's are my card of choice these days. Shooting JPG, the buffer seems endless.

Matthew

A 512MB Sandisk Extreme III is $50 at B&H.

-Zeke