can I clone my HDD to an external HDD?

Hi I would like to clone my 40 gig windows xp hard drive to my 500 gig external maxtor I only have 800 mb left on my internal 40gb drive and I have put all of my other documents, music photos etc on my external but I have some very large programs that I need to keep. I have went into add/remove programs and removed everything I dont need but that is still not giving me any space so I was wondering if I could clone or image my windows and all of the hidden files and programs to my external until I can buy a larger internal? my pc is a hp pavilion 7955 P4 1.50GHZ, 1.49GHZ, 1.25GB of Ram this is from the system information also can I install a 1TB drive in this pc? Also my external drive is a Maxtor one touch USB 500 GB.::confused

 

Thanks Pldor that is 3 times more space than what I have now is there any kind of way I can clone this drive to my external and would my programs still work?:confused

 

Sorry for the misspell of your name plodr

 

Are you meaning to boot from the external drive? It may be possible with significant modofications but under normal circumstances Windows won't boot from an external drive. However, if you mean to clone your system onto an external drive then install that drive into your PC to replace the old drive, you can do that.

 

I will not be installing the external drive into my PC, what I want to do if possible is clone my windows and programs to my external drive and then delete most of the big programs from my C Drive to give me space until I can get a larger internal replacement drive, but my dellimma is will I be able to use the programs on my external drive to run their programs once I delete them from my main hard drive? am I making any sense? because it sounds complicated as I am typing it:confused