Below is my CTE effort, which won't work on SQL2000, but which does consider multiple fkeys.
I'm not entirely sure what the 'standard' convention is, as it seems to depend on how you create your foreign keys. I think it might even have changed between releases / service packs. But the essential elements have remained...i.e...pktable, fktable and numeric counter. The script below should be quite simple to customise to taste.
;with keycouples as
SELECT fkeyid, rkeyid, count(*) as keycount
GROUP BY fkeyid, rkeyid
refs.constid as constid, refs.fkeyid, refs.rkeyid, row_number() over (partition by refs.fkeyid,refs.rkeyid order by refs.fkeyid , refs.rkeyid) as keynum, coup.keycount
FROM sys.sysreferences refs INNER JOIN keycouples coup on refs.fkeyid = coup.fkeyid and refs.rkeyid = coup.rkeyid
quotename(quotename(object_schema_name(rr.fkeyid))+'.'+quotename(object_name(rr.constid)),'''') as objname,
object_name(rr.rkeyid)+'_'+object_name(rr.fkeyid) +case when rr.keycount=1 then '' else '_FK'+cast(rr.keynum as varchar) end as newname
FROM referencerows rr
SELECT 'exec sp_rename ' + objname + ','+quotename(newname,'''')+','+quotename('OBJECT','''')+' GO' FROM chunks
order by objname