was using avg 7.5 on my old celeron ,
it cannot hold 8.0 or 8.5! 
Are they any Av’s Left for Win98??
I got some old pc’s still running 98.. can’t take XP..
Trend micro office scan still supports 98.
I believe the old version of nod 2.7 or something still supports. Its also light on the system.
some versions of QUICK HEAL work on 98
avoid quick heal, its a P.O.S. kthxbai
Avast will do fine. Sys requirements as per Avast:
For a computer running Windows® 95/98/Me:
486 Processor, 32MB RAM and 100MB of free hard disk space.
For a computer running Windows® NT® 4.0:
486 Processor, 24MB RAM and 100MB of free hard disk space and Service Pack 3 (or higher) installed
For a computer running Windows® 2000/XP® Workstation (Not Server):
Pentium class Processor, 64MB RAM (128MB recommended) and 100MB of free hard disk space
For a computer running Windows® XP® 64-bit Edition:
An AMD Athlon64, Opteron or Intel EM64T-enabled Pentium 4 / Xeon processor, 128MB RAM (256MB recommended) and 100MB of free hard disk space
For a computer running Windows® Vista:
Pentium 4 processor, 512MB RAM and 100MB of free hard disk space
The program itself requires about 60MB of hard disk space; the remainder of the recommended space is reserved for the virus recovery database file and its index (VRDB, also known as the “integrity database” from the previous version).
A functional MS Internet Explorer 4 or higher is required for the program to work.
This product cannot be installed on a server operating system (Windows NT/2000/2003/2008 Server families).
Cheers…