I decided to take a bard with a few levels of rouge and I was wondering what is the lowest amount of points I could put into spot, disarm traps and lock pick and have them be effective all game?

You'd need quite a few points for it to be effective all the time. I'm not the one to ask. Rogues ain't my bag

I'm not the right person either, but he'd probably like to know if you're talking of Icewind 1 or 2.

If you're talking about IWD2, I don't know what the max DC on locks and traps is but I took a variant of the Ultimate Powergaming Party on my last run through the game, and I did follow the suggestion of only a single Rogue level with my 'Rogue' character. Cross-classing into Open Locks and Disable Traps presented me with no difficulties throughout the game.

Of course, if you're not into powergaming, you likely won't go for the maxed out INT (and it would be a bit silly to do that anyway, since Bard spellcasting relies on CHA), so you'll have fewer skill points to spend, but you still should be able to get by if you cross class your skills.

Thats actually what I ended up doing with my bard(x)/rouge(2). Gave her max int and cha and eights and sixes in everything else. Made it through normal and HOF mode with her just fine and never met a lock I couldn't pick. She was the party spokesman too since my paladin likes to turn down rewards.