How much base memory to allocate for the virtual machine?
 

My laptop has 1 GB RAM.
I today installed Ubuntu 12.10 in my virtual machine. Host OS is Windows 7.
I allocated 480 MB of base memory for the virtual machine. The Ubuntu was running so slow that it was completely useless and time wasting to run that. Everything I was doing in Ubuntu was happening in slow motion. Not only this, my host OS Windows was performing very very slow and impossible to work.

So, is there any go orelse I should remove my virtual machine.

1GB is too low to run a VM on Windows 7. Windows 7 alone has a minimum requirement of 1GB RAM, for Ubuntu also 1GB of RAM is recommended. In your case a native install may be the better solution instead of using a VM.

Yes you are right TobiSGD.
I would install it directly in my hard disk.
The .iso file I have downloaded can I use it for the direct installation.
If so , how?

Also please tell me whether there are any means by which i can increase RAM and how much would it cost. Also, i should increase to how much 2 GB or 4 GB or .....

How much the RAM costs depends on what type of RAM you need, if you can increase the amount depends on your laptop.
To use the ISO file you downloaded for installation either burn it to a CD (as image, not as data-CD) or use programs like Unetbootin to copy it to an USB flash device.

Here are easy 1-2-3 instructions (with screenshots) to install Ubuntu on your computer.

http://www.ubuntu.com/download/help/...desktop-latest

You should test-drive it first (try without installing) to see if performance is satisfactory on your hardware.

If your computer is too slow for Ubuntu (what are your hardware specs?), then you can try Xubuntu or Lubuntu. (Both of these offer a "lightweight desktop environment" as opposed to the bloated Unity interface that is the default for Ubuntu these days. The install process is basically the same as in the link above.)

Windows 7 should have at least 1G ram. Ubuntu should have at least 1G ram. More ram is ALWAYS better!

Virtualization, Memory and Fun!
 

I agree, when working with virtual environments on a computer (laptop or pc) put in as much RAM (memory) possible. Of course money is also a factor.

Anyway I wish you lots of fun with virtualization. It's very interesting stuff to experiment with and to learn from in the process.

Cheers,
Marc.