Doubtful you'll find any current commodity PC (Dell, HP etc.) with native PCI support, or even with a PCI slot at all, not even on a high-end X79 box (no PCI slots on Alienware X79 afaik).
So if you want to keep using your Layla 3G, then custom-built would be the way to go, with a native PCI motherboard (B65/75, Q67/77 or X79) to be safe (although I've seen a few unconfirmed reports of some PCI interfaces working on Z68/77 boards).
EDIT: recall now that a while back when I was looking into notebooks, I did come across some biz/corporate desktop Q77-based PC offerings from HP/Compaq (or maybe it was Dell?) with native PCI slots. There was one model with 3x PCI slots and another with a single PCI slot which could both take full height cards. I do remember that the model with 3x PCI stood out at the time, because I hadn't come across any Q77 motherboards with that many PCI slots (almost all are microATX with only 1x or 2x PCI), and also because it could be set up in either a tower or desktop configuration.
Not sure about the pricing as I wasn't shopping for a desktop, but do recall it was available with up to an i7-3770 cpu (not the "K" version cpu, since Q77 doesn't support overclocking), so could make for a pretty powerful system. Anyway, might be worth looking at "corporate" and "business" line PCs.
post edited by Goddard - 2013/04/07 20:57:52