Canon released new firmware today for the 300D
It improves the reliablility of Remote Capture (controlling the camera from your PC and capturing pictures) as well as other PTP and USB reliability issues.
The English link is here
http://web.canon.jp/Imaging/eosdigital/E3kr_firmware-e.html
Just copy to a freshly formatted Compact Flash card, place the card in the camera and make sure that you are using a fully charged battery.
There was some discussion in the Dpreview forum that the firmware upgrade would correct underexposure of flash photos. The upgrade has made no difference in my case but there was no mention of this in the Canon info.
Regards
John
Having owned one of these for less than 24 hours, my tests suggest under-exposure when flash is used. I was relieved when a search threw up this thread, suggesting that the issue was not peculiar to my particular camera. Is anything more known about the problem, please?
Chris
The topic of Flash Exposure Compensation seems to generate a great deal of heat in the various forums.
It appears that Canon included the facility to perform FEC, but did not provide any way of setting it.
http://revolution.cx/rcx/fecset.htm
allows it to be done. Shades of DV-in enabling my Canon DV.
Chris
This is excellent information that I had missed on DPreview.
I recently bought an external Speedlite 550EX which allows me to set flash comp, but it seems daft not to have 2/3 'set all the time' via the FECSet util.
FYI the 550EX is a fantastic peice of kit. When I decided to buy one I was horrified to see it priced at nearly three hundred pounds.
Jessops recently started doing them for £269 but I saw it for £229 at http://www.buyacamera.co.uk/
I printed the page out from buyacamera and took it to Jessops who will "price match at their discretion" - which my local branch did (£236.95 to take into account post and packing that I would have had to pay buyacamera)
It is rather annoying that my present dedicated EOS flash is all but unusable, even in 'manual' mode (which is still A-TTL). I've read much about the merits of the 550EX but it seems an awful lot of money for a flash. 
FYI I've been watching byacamera for the price of the 300D with lens kit. Interestingly when they had no stock it was £812 but, as soon as they had some to sell, it became £860. For the moment my main concern is to sort out the on camera flash and the FECSet utility seems to do that.
Installation was straightforward and the utility worked as advertised. Photograph properties shows 'FEC +2/3' and initial results are more pleasing, to my eye at least, than the default setting.
Chris