Will it be more money for me now if I don't take it out?
Will it be more money for for my retirement if I do?
The difference will be the existence of a match and tax-deferral. If there is a match then you will have an instant 100% gain on the amount that is matched.
From a tax standpoint, putting some in your 401(k) now will reduce your taxes this year - you will instead pay tax when you withdraw the money at retirement (the withdrawal will be considered "income" at that time).
Other decision points:
- Are you saving for retirement now? If not, when do you plan to start?
- Do you have better uses for the money (pay off debts, etc.)
If there is no match, but you still want to add to retirement savings, then you could alternatively put the money in an IRA, which will give you more control over your investments than a 401(k) (which could be good or bad, depending on how investment savvy you are).