the Macbooks are great, if you have the money.
Apart from that, if sufficient RAM and CPU are your only basic requirements, I don't think the Manufacturer or model really matters. Make sure you get a Intel core duo mobile CPU though, they are much more efficient than those from AMD, as far as battery life goes.
Standard 15'' Notebooks with the Intel® Core 2 Duo T5500 Processor and 2GB RAM come at less than 1.000,00 € these days. But that's only 1,66 GHz.
If you want more CPU power, for example the Intel T5600, T7100 or T7200 processors, you'll have to spend a little more.
However, the smallest Apple MacBook has the Intel T7200 Processor @ 2,00 GHz, and if you do want those 2 Gigs of RAM, you can always upgrade, which leads to around 1.219,00 € for the white 13,3'' MacBook with 2 GB RAM. Sure, the screen is a bit small at 13,3'', but it's probably the cheapest way to get hold of a 2,00 GHz CPU.
And Mac's are very well suited for use in Audio recording.