UK ISDN LAN modem/router recommendations (maybe software solution?)

i have a small home network of around 5 PCs running windows' OS 98 xp 2k.

i currently connect to the internet via a "3Com office connect LAN modem" which basically handles all my ISDN data calls for my PCs automatically

now this thing is kinda getting old and im looking for a replacment hardware or maybe software, must be pretty cheap tho as im getting ADSL in my area in around 6 months so only needs to last till then.

we often use 2 seperate simultaneous calls (one for my dad other for my online gaming, so i dont get lag)

anyone have any solutions to this problem? im open to all suggestions!

thanks!