PC slow performance. Hi there,I just want to ask for an advice about my pc.I own a P4 2.8ghz

Question

Hi there,I just want to ask for an advice about my pc.I own a P4 2.8ghz processor. I just replace the motherboard 6months ago I think, After 3-4 months it start to slowdown on boot. It took 2-3minutes before I can log-on. And while on GUI when I open 3-4 applications at the same time it hangs.. I dont have the budget to purchase a new set of pc. What can I do to lessen or prevent my PC from hanging and to speed it up.Thank you very much for your help.