The second try in that posted log, was that a new disc? It looks used - if you compare the sectors available with the first burn try in the upper part of the log.
I 01:24:24 Destination Media Sectors: 3,827,520
Never heard that to much RAM slows it down. Easiest is to go to your manufactures homepage and look at the specs for the memory it demands.
DDR3 1333 8GB 2x4GB (Kingston) is around $59 here in Sweden and DDR3 1333 4GB 1x4GB CL9 Adata is $28 (incl 25% VAT)
Had a Vista 32 bit system with 2GB RAM and an addition up to 3GB made a notable difference in speed.
Running Windows 7 on a 3GB or a 4GB/8GB on a 64 bit system, can't say I noticed any huge speed increase.
In most cases the troubles comes with the hard disk if it's used for heavy writing with another application on the same time as you burn. But then, modern burners have the buffer under run function that resumes the burn if the buffers go empty.