You should consider diagnosing why you are getting lockups first. Adding more hardware could possibly make things worse... for example, if it's a weak or insufficient power supply, etc.etc.
I'd strongly recommend against the 2006 you are looking at as it will be a step-down from your 9600 Pro. The AIW 2006 is basically a 9600 3d card wise, which has lower clocks than the Pro or XT... so you'll see a drop in 3d performance.
On your current lock-up problem- have you tried reducing AGP to 4x and disabling Fast Writes in SMARTGART? Just launch the Catalyst Control Center, go down to the Smartgart area and adjust to 4x + disable fast writes. It will want to reboot- do so. On reboot, revisit Smartgart and ensure the 4x/fast writes off took/saved... then test some games. MANY VIA chipset motherboards have problems with older Radeons at 8x/fast writes... and this would not change with an AIW 2006.
As far as secondary tuner boards, I'd strongly suggest the Hauppauge line of cards over ATI. I have several ATI AIW cards and Tv Wonder cards and have had nothing but problems and grief from them. Their new HD Wonder is a decent product, as well as some of their older TV Wonder products.. but in recent years they have gone way downhill with wdm driver support and software. I'd urge to get an individual 3d card (ATI or NV) and a secondary tv-tuner for PCI (preferabbly Hauppauge).
Hope this helps!