Need help overclocking Barton 2500+ on AsRock K7VM4 and video capture questions

I recently purchased the following setup:

-Athlon XP 2500+ Barton retail with stock heatsink/fan
-Kingmax 512 MB PC2700 DDR
-Maxtor 120GB 7200RPM, 8MB cache, ATA-133
-AsRock K7VM4 MB, VIA KM400 chipset with onboard PCI bus S3 Uni-chrome
video chip sharing 64MB system memory
-Winfast XP2000+ Deluxe TV turner card
-Generic 400 Watts PSU/Case

Using the onboard video. I've overclock the 2500+ to 380 FSB (from
1.83G to 2.09G) with default 11x multipler and WinXP runs perfectly
24x7 and watch TV without any problem excpet when I do anything video
intensive like following tasks:

-While recording TV program with my TV turner card, WinXP would freeze
or reboot maybe 5 to 10 minuties into recording. CPU usage stay around
85-90% during recording and I've plenty of hard disk space and free
physical memory left.
When I check the BIOS, I see that the CPU temp reached about 50C (idle
temp is about 45C). Even without overclocking, during recording the
CPU usage would be constantly at 95-100% and sometimes when I just
open explorer to browse for files, the video would freeze. I've
looking at the CPU temp everytime it freeze and it's always 50C.
BTW I'm recording at 640x480 capture resolution and 30 frame/sec using
Divx codec.

-When I play games like Need for speed 5, simcity 3000, or quake 2 it
always freezes on me and sometimes they won't start.

I've also tried to raise CPU clock to 194, it won't even boot. The
best I can do is 192 CPU clock. And when I use default 166 CPU clock
and try 11.5x multipler, that won't boot either. So I guess my Barton
2500+ is probably still lock, unlike many whose CPU come unlocked
already. But I don't worry about that, I'm happy being able to
overclock to 190 CPU clock as long as I can resolve the unstability
while recording and occassionly game play.

Also with the CPU core voltage raised 5% (BIOS feature), it didn't
help and shorten the CPU heat up time.

Here're my questions:

Is the onboard video not able to handle the overclocked FSB or the
amount of data during TV recording?

Is my CPU overheating at only 50C? The motherboard have CPU overtemp
auto shutdown. But I don't suppose 50C is too hot to auto shutdown.

If I can lower the CPU temp with larger heatsink/fan, would that help?

Would using a seperate AGP card (i.e. MSI GF4 MX440 AGP8X 64MB DDR)
help with CPU usage running high and freezing up during recording?

Is the MSI GF4 MX4400 card able to handle TV capture at high
resolution? What would be a good budget card for the task?

Any comment or suggestion appricated,
Thanks
Bill