Right i would assume they are roughtly they are roughly the same i could say which is better, but i would go with the P4 with some hope of OC'ing it.
bewareb the celeron is soc 479 and the P4 could be PGA423 or a 479. make sure your mother board is spec.
also the if the P4 is 423 and you dont have the right board, run like hell from it, because it uses rd ram (rimbus) which s great ram for it's time but it's deadly expensive.
how much do you intend to spend on these because you can get a new dual core celeron for £33 ($66)
if you get these chip and intend to run XP or Ubuntu make sue you have at least 512 as it is pain stakingly slow
the athlon 4800 is a much more powerful CPU good enough to run vista with 2GB of ram.
I got another pc (athlon 4800+, 2gb of ram, 9600gt, all OC'ed) but I looked for a PC for my brother. He doesn't know that much about computers and the only game he plays are Wolfenstein ET online and Red Alert 2. This morning a friend of my offered me a choice between two computers which i may have for free.
I know that the CPU's have different sockets, but that ain't a problem. I get the whole platform (MB, RAM (512MB), PSU, etc) and both platforms are almost identical, except for the socket and CPU. So that's why i needed to know the difference between the CPU's.
I'd go with the Celeron, it is probably Northwood based, which was a good improvement over the Willamette core of the P4 listed. If he just plays Red Alert 2 and the like, either should work, as I ran RA2 on a 450MHz PIII back in the day.