Can u upgrade the processorto anything high then a amd duron(tm) 1.29ghz

yes, depending what motherboard you have. almost all of them will support 1.4 ghz

Here is MSI's list:
http://us.msi.com/index.php?func=prodcpusupport&maincat_no=1&prod_no=527#menu

Go to the motherboard website and download there the drivers.

Your motherboard probably does not support that speed, without a bios upgrade.

Download a small utility called CPUID from http://www.cpuid.com or use this direct download link "http://www.cpuid.com/download/hwmonitorpro/HWMonitorPro_106.zip". Using this utility you can analyze your system hardware statistics and also you can find the RAM capacity supported in your system along with various other RAM parameters. It will also show you the available free RAM slots to use, as well. I hope this is useful to you.

Your motherboard has a good support for various Processors. If you want to go for the latest then you can go for Palamino core Athlon 4.Its compatible all the KV7 series boards but all you have to check is "Till WHAT clock speed can your board support?" .

Regards,
Sai.

Here is the list of compatible processors for your motherboard:

AMD Athlon 650, 700, 750, 800, 850, 900, 950, 1.0G, 1.1G, 1.2G, 1.3G, 1.33G, 1.4G (Thunderbird)
AMD Athlon MP 1.0G, 1.2G, 1500+, 1600+, 1800+, 1900+, 2000+, 2100+ (Palomino)
AMD Athlon MP 2000+, 2200+, 2400+, 2600+ (Thoroughbred)
AMD Athlon MP 2800+ (Barton)
AMD Athlon XP 1500+, 1600+, 1700+, 1800+, 1900+, 2000+, 2100+ (Palomino)
AMD Athlon XP 1600+, 1700+, 1800+, 1900+, 2000+, 2100+, 2200+, 2400+, 2600+, 2700+, 2800+ (Thoroughbred)
AMD Athlon XP 2500+, 2600+, 2800+, 3000+, 3200+ (Barton)
AMD Athlon XP 2000+, 2200+, 2400+ (Thorton)
AMD Sempron 2200+, 2300+, 2400+, 2500+, 2600+, 2800+ (Thoroughbred)
AMD Sempron 2200+, 2400+, 2500+, 2600+, 2800+ (Thorton)
AMD Sempron 3000+ (Barton)
AMD Duron 600, 650, 700, 750, 800, 850, 900, 950 (Spitfire)
AMD Duron 1.0G, 1.1G, 1.2G, 1.3G (Morgan)
AMD Duron 1.4G, 1.6G, 1.8G (Applebred)
You motherboard uses a "Socket A" CPU and therefore has limits to how high you can go.. I would recommend the XP 2200 or 2400+ as a good choice, but you can make your own choice.

Look for socket A processors and ignore the XXXX+ and focus on the XXXXMHz rating (the MoBo's manufacturer's support site will give you the max processor your Board will handle). Since you mention that your MoBo is 4 to 5 years old, you'll probably better serve yourself to replace the MoBo and processor (you'll be able to upgrade to a much better/faster processor by upgrading both, and shouldn't cost that much more), and probably be happier with the result. You may want/need to upgrade your Power supply while you are at it too.

AMD 2800+ is 333MHZ while
AMD DURON 120MHZ is just 200 MHZ

It means that the board supports 333MHZ not 200MHZ.
Well it's not compatible...

Depends on which AMD processor you would use. If Duron you could go to 1.8Ghz. If you use Athlon XP you could go to 3200+. Athlon MP 2.1Ghz and regular Athlon 1.4Ghz.