Greeitngs friends!
I have a desktop with and external usb dvd writer. I want to know if there is an adapter which allows me to turn the dvd into an ide drive so I can boot from it (the board is old and does not provide to boot from and usb device , I have a linux distro in a dvd disc which I want to add to the hard disc)

There has to be one out there somewhere, but I can't seem to find one that goes that way. Plenty of adapters to turn an IDE drive into USB. But not many people want the other way around.

Internal IDE DVD burners are very cheap costing as little as $23 (http://www.newegg.com/Product/Product.aspx?Item=N82E16827106228). Why not just get one and install it?

You can also remove you USB drive from the USB enclosure and install it in your system. It's just an IDE drive stuck in a USB enclosure.

As jlreich stated, either take the drive out of the enclosure and attach it directly to an IDE/ATAPI slot (assuming it is neither a SCSI nor SATA device inside) or grab yourself a PCI USB2 card. This only has the potential to work if you can set the BIOS to boot-up a USB Optical Device. If not then SBM (in my sig) might or might not work depending on the age of your PC, which is unlikely to be a newish one if it has no USB ports. Also like jlreich stated, I would just go for a new drive unless you are in a rush of course.

As jlreich stated, either take the drive out of the enclosure and attach it directly to an IDE/ATAPI slot (assuming it is neither a SCSI nor SATA device inside) or grab yourself a PCI USB2 card. This only has the potential to work if you can set the BIOS to boot-up a USB Optical Device. If not then SBM (in my sig) might or might not work depending on the age of your PC, which is unlikely to be a newish one if it has no USB ports. Also like jlreich stated, I would just go for a new drive unless you are in a rush of course.

The computer has usb 1.1 connectors but the bios does not provide any option to boot from nothing else besides floppy,cdrom ,floptical (which I do not know what the hell is this)

If there is no mention of USB in the BIOS boot options it is most unlikely you would ever be able to boot from any USB devices - directly or indirectly from a boot manager. USB 2 would not generally be mandatory though would obviously be better than 1.1 when copying files during setup. It would cost you little to try SBM (from a boot floppy) and see if it can even "see" your external optical drive attached to your current 1.1 port.

Flopticals (http://en.wikipedia.org/wiki/Floptical) do not abound.

Most of the USB optical drives are just an IDE optical drive + an IDE to USB convertor all put in a nice case. Pop open the case and you can install the drive in your PC using the IDE cable.