I finally finished upgrading my HTPC to Windows XP MCE 2005 running an ATI HDTV Wonder tuner card, so I record in HD. For the most part, it works great, although I have bit more driver tuning and configuring to do.

I also have a Hauppauge PVR 250 as a second tuner card for the non-HD channels, and so I can dual record two shows at the same time.

When I record a single HDTV show at a time, it works fine. Smooth playback, no skipping, etc. However, when I record an HDTV show, and a non-HD show at the same time, the HDTV recording gets sluggish, skipping frames, etc., while the non-HD show records fine.

I'm running at 1080i resolutions through DVI to my Sony 50" HDTV. I'm using nvidia's DVD software decoder, and the latest nvidia drivers for MCE.

So it seems my system doesn't have enough horsepower to record 2 shows at the same time. I'm trying to figure out where the weak link is before I just start blindly upgrading things that may not need to be upgraded. So is it my CPU? memory? video card?

Here are the specs of my HTPC machine:

Athlon XP 2200+
512MB Corsair DDR 266
Dual Maxtor 60GB 7200 drives in RAID 0 for operating system
300GB 7200 RPM Seagate Barracuda ATA 133 (for TV recordings)
MSI Geforce FX5200
Turtle Beach Montego DDS 5.1 SPDIF
ATI HDTV Wonder
Hauppauge PVR-250

So is my best bet to upgrade the memory to 1GB?
Or upgrade my processor to an XP2700+ (or whatever the fastest Socket A chip is, as I don't want to replace my MB)
Or upgrade my video card?

Thanks in advance!