Why is the volume so low on my computer speakers?

On my old no-name computer my old JBL Pro computer speakers could get pretty loud and sound decent too. Now I have them hooked up to my new computer, an IBM NetVista and I can turn the computer volume all the way up and the sound won't go loud enough. This is a real problem on things like youtube and at other sites too; it happens on cd's too or almost any situation where audio is required. It's too bad because I really like the quality of these computer speakers. Any solutions? or do I just have to buy new speakers? If I'm stuck can you recommend other speakers at a reasonable cost? Thanks