Re: cpu upgrade to sse2?
Yes, basically, it improves performance in applications which benefit from it.
I have an Athlon 1.1GHz which runs fast, even when running Windows Movie Maker and videos, so if this is the sort of things you do, there is nothing to worry about.
Windows XP Pro 17" LCD Monitor (1280 x 1024)
nForce3 250 Chipset Athlon 64 2800+ w/ C'n'Q
1 x 512MB DDR400 CL3 SDRAM 40GB IDE 7,200rpm HDD (8MB Cache)
nVidia GeForce MX420 64MB PCI On-Board Audio