Hi, sorry I was out last night.
Errors 00161/00163/00173 mean you need to replace the CMOS/BIOS battery and update the time, date etc, like you did.. and Error 00301 means a keyboard error. Just press CtrlAltDel past this.. or try using an external PS-2 keyboard..
So, when you startup and then get to the errors, just press CtrlAltDel to restart, then tap F1 to enter the Advanced Settings and try to load Windows in Safe Mode, and let it do a Scan Disk.
It's possible that the machine won't be able to load any hardware drivers for the machine because the CMOS information might have been corrupted due to the flat battery, but try and boot into Safe Mode anyway and see how you get on.
This is a really old machine but still has driver and troubleshooting support at the Lenovo website, and it might be fun and interesting to resurrect.. Hardware Maintance Manual - June 1999: ThinkPad 600, 600E
On pages 109 and 115of the attached pdf file (actual pages 103 and 109), the Li-Ion batterypack part number should read 12P4064 replaces 02K7018.
Battery test utility diskette - ThinkPad 600/E/X
BIOS Update (Diskette) - ThinkPad 600PCMCIA SelectaDock I/II driver for Windows 95/98 - ThinkPad 600, 770
Windows 98 installation supplement files - ThinkPad 600, 760, 765, 770This
is the Setup Guide for the thinkpad 600.
Of course, it may very well load Windows fine after a new battery and a scandisk and you'll find it has Windows 2000 on it, so maybe I'm jumping the gun with the Win98 stuff there, but let me kow how you get on..
Oh by the way, if we are going to be using a different Solution thread this time, can you go back to the other page and rate it as Fixya! so that they can take it off the system? It saves the unrated pages filling up the servers..