Well I did some scouting around on Ebay and I see that the 170l came from factory with a Pentium 4 2.8C HT (northwood).
this would be the chip on Ebay.
http://cgi.ebay.com/Intel-Pentium-4-2-8-GHz-socket-478-CPU-SL6PF-512-533-P4-/120618128115?pt=CPUs&hash=item1c156692f3
It is buy it now at 15 dollars (I make no personal recomendations for this seller)
So that answers your question.
But I have to agree with malmental on this one.
If your really strapped for cash then the 15 bucks would be a cheap upgrade.
BUT if you look on Craigslist right now you can find some nice deals on OEM towers.
I just saw a Dell with a Pentium D 3.0ghz (first dual cores),1gb ram,80gb Sata HD,PCI Express x16 slot, Windows XP Pro with COA for $139 from a recycler/refurbisher with a 30 day warranty.
That is in the New Jersey USA section.
I dont know where you live so pricing could be different.
The point is for under 150 US dollars you would have a much more stronger CPU,Sata and PCI Express which makes a big difference.
Just make sure you see it boot up and that it has a Certificate of Authenticity for the Windows version on it since alot of refurbishers use pirate software.
Just a thought.