Modern dvd writers are NOT meant to burn at 1x. You will more than likely get a better quality burn at 4x than at 1x.
The speed used will depend mainly on the quality of disk you use. Good quality disks can be burned safely and reliably at 12x, if not 16x. For medium quality disks 8x (or half of the stated speed) works great, and is what use myself. For crappy disks, or if you're just really paranoid, then 4x is the lowest you want to go. It should give you a good burn nearly every time regardless of the disk used. It really doesn't make sense to burn slower than 4x.