Paul,
We are using a server and always have but I believe AC and any of the interfaces work in a P2P set up. We have used Quest for a long time and pleased with their services and had been receiving a download into a folder on our server of which we had to manually import into each patient's file in AC. This required an MA to do this every morning and I was so happy to have the final install for the interface. We tried Labcorp because Quest interface wasn't ready and it was difficult to get Labcorp to do it right and I gave up since we hardly use them and the Quest interface was coming soon.
We had confusion between AC requiring the physician to pay for the interface first prior to having an invoice sent that Quest would pay (Jon says Labcorp gives no trouble). It is $500 but you can try it for free for 30 days. I recommend calling your local Quest Rep to have it set up and promise to pay you back for the interface. Not sure why Jon just doesn't send the invoice to Quest and let them handle payment.
Once we had this straightened out (paperwork via Quest Rep for approval) then a Quest comp tech came to our office and installed or updated the program (lightning)o our server and we were automated. They basically place a folder wherever AC told them that the interface looks for the labs and imports into each respective chart automatically. The first few times we did it took hours because it was downloading from 2 months prior and since we didn't use AC to order we had to match up names correctly. It is now a lot faster. We have had it for a couple of weeks now and while it is different than what we are used to seeing on a pdf file, it is certainly automated and in the patient's chart via 1 click. That frees up the MA to do something else. I am always for automating any process, it is certainly worth it. The Labcorp interface works same way and it is a separate fee for each lab and it is a one time fee.
If I missed answering anythinng, feel free to email me.