I assume you know why the CPU "burned" and have corrected that problem.
You might try just looking at the part numbers on the chipset, if
they're not Intel chips you may not get much info from Intel.

Are you sure you're not just going to burn the "new" processor then?

Anyway, http://www.acersupport.com/notebook/html/tm630.html claims
that the chipset is "ALi M1671 and M1535+" (for all versions of 630).
Other sources says "ALi ALADDiN-P4" which is the same, so it should be
correct.

However, almost all links to this chipset on ALi's pages are dead, so
it seems very hard to find out what intel chips it might support.

The P4-M was evidently built up to 2.6 GHz, and a cursory inspection
suggests that the 2.0 GHz and higher used the same voltages (and other
easily visible attributes).

Cooling might be a problem, but the TDP seems to be not THAT
dissimilar up to the fastest P4-M (and the rest looks even closer),
though the two older of the four P4-M 2.0GHz lists *two* TDP figures,
if it's one of those and the lower figure is right (which it probably
isn't!) it's a 70% TDP increase... However the TDP isn't in itself a
guarantee that it won't overheat, but it looks slightly less
improbably than I had originally assumed.

The BIOS might also cause problems, it might refuse to start unless
the BIOS "recognize" the CPU model and since it's a laptop (and old!)
this list might be very small.

None of these are necessarily showstoppers, it COULD work, but unless
you are carefull you might be out with that money and still end up
having to buy a new laptop!

Also, the CPU isn't exactly widely available, pricewatch found only
one source and while they had several different models the fastest
they had was 2.0GHz. eBay lists more at lower prices, but most seems
to be pulls from machines, and even the "new in box" from a "good"
vendor might be more risky than an internet shop (and be careful with
that eBay listing, it includes variety of Mobile P4's in addition to
Mobile P4-M).

If you go for a 2.0 GHz you might want to try to match the sSpec on
the original CPU, to reduce risk of trouble as much as possible
(StallionTek had 3 of the 4 possible sSpec and many of the eBay
listings also includes the sSpec).

But I think you're far better of buying a new laptop!
Laptops are much fiddlier and complicated to do major surgery on, the
Mobile P4-M series of CPUs is no longer available and it's already
burned the original CPU...

http://support.intel.com/support/processors/mobile/pentium4/
http://processorfinder.intel.com/scripts/list.asp?ProcFam=826&CorSpd=ALL&SysBusS
pd=ALL&Pkgtype=ALL

http://www.stalliontek.com/SearchResults.asp?Cat=113&SortBy=Title&Page=2
http://listings.ebay.com/aw/plistings/category86716/index.html

http://www.ali.com.tw/eng/products/ali_powered_products_m1671.htm
http://www.digit-life.com/articles/alialaddinp4/
http://www.tomshardware.com/2002/01/23/a_lackluster_premiere/index.html