what are the best interface/firewires (and cheap) should i get between the keys and pc for a godd transmition..
firewires? usb? pci?
M-Audio Delta 44
Behringer FCA202 F-Control FireWire Audio Interface
A bit of an oxymoron there because you cannot have the best and still have it cheap, there will always be a compromise between price and performance.
Like I said earlier, decide on how you want to operate. It seems your heart is dead set on getting a mixer but that is not always the best route. For ex., I prefer to connect my synths directly to my audio interface to minimize noise and other possible sources of coloration that's why I have a multi-input interface (18 ins at full tilt, 8 analog with the rest digital). The Emu also has 2 XLR inputs for direct connection of mics with phantom power - it's this number of I/O that's one of the reasons I have gone mixerless.
In order of the fastest data throughput to slowest among the interfaces you mentioned, its: pci, then firewire, and lastly usb. That's why I don't like to recommend usb devices unless your I/O needs are not that high but if you intend to track more than 4 channels with the minimum of risk, firewire and pci is the way to go. Firewire seems to be the safest route since some manufacturers are making the transition to pcie right now.
If you want to go firewire, the best right now is RME but it ain't cheap. Following a close second are Mackie with the excellent preamps in their Onyx line. Among the best in price/performance ratio, IMO, are the Presonus Firepod/Firebox. All the rest are either too new or risky to chance with yet (Alesis firewire mixers seem to be giving some users quite a few headaches, e.g.).
Best bang for the buck for pci interfaces? M-Audio Delta 1010LT. Unfortunately, this is now considered a discontinued product but at $149 for 10 ins/outs, it's a steal. Not the best converters and unbalanced operation, but stable drivers and it works with almost all software, if not everything. Just research if it's compatible with your mobo (usually is), try to stay away from Via chipsets except for the KT800.