affordable d/a or audio->usb ?

so i do all my mixing otb. but i'm getting to a point where running an rca -> 1/8 in mic jack on my laptop is just not cutting it.

all i really need is something that's dual input -> usb. or firewire. with good but not ridiculous sound quality (i've looked at the apogee duet and some others, but problems were $ or the fact i don't use a mac).

anyone have any affordable ideas?

not sure what "affordable" means as far as range so i'm gonna start low, Most these products I've used while working for sam ash.

http://www.guitarcenter.com/Lexicon-Alpha-USB-Audio-Interface-103840849-i1126259.gc

I use a firestudio project this a cheaper version but no difference in quality

http://www.guitarcenter.com/PreSonus-FireStudio-Mobile-10x6-FireWire-Recording-System-105625826-i1471883.gc

an even cheaper version

http://www.guitarcenter.com/PreSonus-AudioBox-USB-2X2-USB-Recording-System-104841978-i1388074.gc

and then what I have, and live and die by

http://www.samash.com/p/Presonus_FireStudio%20Firewire%20Audio%20Interface_-49974321

Personally I'd go with a pci card interface before usb or firewire, never tried usb or firewire but usb always seemed suspect to me.

USB is suspect as hell. It's flawed for audio/ video purposes for a number of reasons. Read the comparisons between USB and Firewire:

http://en.wikipedia.org/wiki/Universal_Serial_Bus#FireWire

http://en.wikipedia.org/wiki/FireWire#Comparison_with_USB

If you don't feel like reading from those links, the basic conclusion is that Firewire 400 out performs USB 2.0 in most real world (not theoretical) applications.
I have no comment on USB 3.0 or direct PCI connections....

Anyways, I use a Focusrite Saffire Pro 24. For the money, it's nice, I like it.
http://www.guitarcenter.com/Focusrite-Saffire-Pro-24-106215171-i1460804.gc

def. suggest the firewire over usb as well