I am not sure how closely they compare, but my AMD dual core laptop struggles with folding SMP units. It might be better to set up two slots for uniprocessor in the v7 client. That client will only download one WU per slot at a time, but it can be set to download the next one when you reach a certain percentage of completion, from 90% to 100% IIRC.
As Chumly said, if it can't upload, it will still pull down another to chew on. Of course, you have to be connected to the net to download, so the upload will try at the same time. DL is faster than UL, obviously. If you were limited on connect time, it is conceivable you could connect long enough to grab the next one and disconnect before the UL completed, and then allow the UL to complete at another time. I think this would generally be discouraged, but it would keep your machine folding.
If you do go the uniprocessor route, the delay in UL will have little bearing as the timeout and expiration is usually 30 days or longer on those. SMP timeout and expiration are much shorter, around 7 and 14 days respectively. The longer you delay the UL of SMP, the more it cuts into the Quick Return Bonus (QRB).
So, welcome back! Any folding is a help for the program.