I have the DTT3500's here Fluke (both analog and digital connectors), and for DVDs and such, digital is the only way to go with the Herc, primarily because the DD / DTS discrete channels are only really output on the digital outputs. The downside to these speakers is that the analog connectors only support 4 channels (2 front / 2 rear) on the speaker end. What this means is that even though my Herc has more outputs, I have no inputs on these speakers for them.
On to the 5300's:
I've considered replacing my DTT3500's with the 5300's, for two reasons. The first is that although the 5300's lack digital connections (including the Live-specific SPDIF connector), they do appear to have 6 discrete analog inputs. This is perfect for the analog outputs on my Hercules card. The second reason is that I have no less than three standalone DVD players in my house now, for use watching movies or other content that has DD / DTS content, so I don't need the digital outs on my Herc for that. (If you needed to use the digitals for editing music / audio, say to those Sony digital tape decks or something, the ports are still free too- BONUS).
For gaming and other 3D audio on the PC, the analog outputs are the best choice with the Hercules, and the 5300's seem to be the best overall match for this use with this card available at the moment, short of buying a standalone DD / DTS receiver with 5.1 (6 channel, 5 mains + sub) analog inputs, and driving a set of HT speakers with that. This last setup would allow the full use of both the digital outputs (for movies and stuff on DVD) as well as the analog outs for gaming and other PC applications, but usually can be expected to run much more $$.
1) If he plans to use the PC for DVD playback, you don't want the 5300's (no way to output the DD / DTS streams to them from the Herc).
2) If he doesn't need DVD playback on the PC, but wants to play games or other DS3D / etc. PC audio using all the channels, the 5300's are choice #1, despite what the speakers' component ratings may be. These speakers will allow 6.1 analog output from the soundcard, which is currently the only set to do so that I've seen yet (all others use the front / rear stereo type connector, and either interpolate the center / sub, or completely ignore them).
3) If money's not an issue and/or the system will be used as in both 1 and 2 above, then the cheapest DD / DTS HT receiver that also includes 5.1 / 6.1 analog inputs (usually meant for future decoder hookup), built in amplifiers, and the cheapest HT 5.1 / 6.1 (mains + sub) speakers to match, would be the best overall setup. I'd love to do this myself, but I don't plan to spend what a setup meeting my expections would run.
Good luck with the hunt Fluke.