I have just done it this summer
I drove to lebanon in june ,came back in august
roads are fine except some roads in jordan,but they are wroking on them i guess
it took me 33 hours,including a 6 hour sleep on the saudi jordanian border which i highly recommend doing cz you wont be able to continue to lebanon without any rest
you need a visa to go into saudi arabia that needs approx 2 weeks to be processed,and the other ones (jordanian and syrian visas) can be gotten on the border,but you have to pay
i had an irish friend with me,he had to pay 20 dollar approx. on each border
you have to know that in saudi arabia,the roads are a bit confusing(being changed all the time) so you have to plan it well before going,a gps would be perfect or a good map
finally dont take any girls with you cz they wont let them in to saudi arabia ;) (unless she is your wife )
if you want my personal opinion,fly there.cheaper, safer and less hastle
cheers