when you say it lags when you change channels, how much by?
I'm not familiar with your TV card, but with digital it usually takes a few seconds (at very best) to change channels. I think Analog is quicker, but timeshifting will slow things down too. Does your TV card have hardware encoding? The cheaper ones don't and as a result make your CPU do all the work. It sounds like this is what is happening here.
If you do have a software TV card, rather than upgrading your system, you will get a much better performance boost if you bought a new TV card. If you still want analog, get a Huappage 150MCE. It will work great and you can still use your old card for watching as well. (it's also relatively cheap compared to a system upgrade).
I'm not familiar with your TV card, but with digital it usually takes a few seconds (at very best) to change channels. I think Analog is quicker, but timeshifting will slow things down too. Does your TV card have hardware encoding? The cheaper ones don't and as a result make your CPU do all the work. It sounds like this is what is happening here.
If you do have a software TV card, rather than upgrading your system, you will get a much better performance boost if you bought a new TV card. If you still want analog, get a Huappage 150MCE. It will work great and you can still use your old card for watching as well. (it's also relatively cheap compared to a system upgrade).