Dell ones are good at the bottom end, but be prepared to buy some more RAM for it, they come underpowered.
I got the Inspiron 1300 on offer for £300, with a £30 ram module from crucial, it runs brilliantly.
The HD is only 40gb, but i have an external drive for all my music, as thats what it all goes on.
Have a look http://configure.euro.dell.com/dellstore/config.aspx?b=&c=uk&cs=ukdhs1&l=en&oc=N09135&rbc=N09135&s=dhs&sbc=ukdhsrsinspn_1300_3
then try upping the HD.