Ubuntu says low space?

-So I've installed Ubuntu 11.04 on my PC which has Vista already installed in it. Now the problem is whenever I boot into Ubuntu it keeps me showing a warning message like, "This computer has low space" for every warning I receive the space gets reduced. For e.g. 1st it shows me there's only 50 MB space and later it shows me there's only 25 MB space left. And the thing is there's more than 10 GB space. Since I'm new to Ubuntu I couldn't solve it on my own. And also I tried to clean the apt folder by running a command but I couldn't do that. Pls help me in solving this. Thanks. Regards10GB of space...WHERE? Post your partitioning scheme. Run your disk utility and see where that space is.
install d ubountu on different drive thn windows.....