Computer output to DAC, which route?


I have disbanded my main system because I am using my computer system more and more. I am going to purchase an outboard DAC for my computer, but I want to know something:
My computer comes equipped with COAX and TOSLINK outputs on the motherboard. Should I use one of those or use a DAC with a USB connection? WHat are the pluses and minuses of each way if any? I am using typical Altec Lansing speakers (good for what they are) but will probably move up to active Dynaudio monitors in the future. All music is sourced from itunes in either AAC or apple lossless formats.

Thanks in advance!
phoenix469
Grace Design m902b headphone amp and ASUS Xonar HDAV 1.3 soundcard. The HDAV 1.3 (several minor variants) is the only line licensed to decode and transmit the audio from Blu-ray at full resolution. You will need Arcsoft TotalMedia player to do this. The soundcard has an S/PDIF out and the amp has an S/PDIF (and an AES) input. The headphone amp also has USB input but USB is limited to 16 bit/48 kHz, which is just not good enough IMO. The 'b' in the headphone amp's model number is for balanced outputs to use with active speakers.
The one box solution:

I have been a pretty hardcore analog devotee, but loved the convenience of digital. Cut to the chase: If you have a Mac server with firewire, buy yourself a Metric Halo LIO-8. There is a learning curve associated with pro gear, but in this case it is worth it. IMHO playback at 44K is easily competitive with an Ayre QB-9, and you can do so much more. It has 8 channels of analog and digital IO, runs at 24/192 and will let you record whatever you want completely transparently (at least to my aging ears). Use Pure Vinyl with it to archive and play records better than direct feed from my (RHEA) phono pre. Sell your current (QB-9) DAC and use it to play back all your digital files. Grab some batteries and do some location recording (haven't done that, but am thinking about it). It is not cheap, but a totally amazing box that is a very good value and unlikely to be outclassed for quite some time. Just don't expect a fancy box to put on display.
I have a question. I have a REGA DAC and a Macbook. I would need either a USB-SPDIF converter or a good mini-toslink to toslink cable. Any suggestions for something not too terribly expensive?
I'm in a similar situation... I have a new Macbook Pro and the DAC from my Audio Aero Capitol with SPDIF inputs. I'm leaning towards getting the Halide Design USB-SPDIF Bridge ($450) along with Pure Music software that works with I-Tunes($129). I have not pulled the trigger yet, but like the idea of the Halide Bridge because it's a USB/SPDIF convertor and a digital cable all-in-one... so no extra digital cable is required, unlike most other SPDIF convertors.

Would appreciate input from users of the Halide Bridge.
is the Halide Bridge Asynchoronous ?
In the same shoes and looking for some advice.
Although at the moment, i'm not too keen on buying a USB Dac only. I would prefer to use my Dacs that i already have.
thanks.