Using sed on 1st column of tab delimited file

Hi all,
I'm new to Unix and work primarily in bioinformatics. I am in need of a script which will allow me to replace "1" with "chr1" in only the first column of a file which looks like such:

1       10327   rs112750067     T       C       .       PASS    ASP;RSPOS=10327;
SAO=0;SCS=0;SSR=0;VC=SNP;VP=050000000005000000000100;WGT=1;dbSNPBuildID=132
1       10433   rs56289060      A       AC      .       PASS    ASP;RSPOS=10433;
SAO=0;SCS=0;SSR=0;VC=INDEL;VP=050000000005000000000200;WGT=1;dbSNPBuildID=129

I would like it to be:

chr1       10327   rs112750067     T       C       .       PASS    ASP;RSPOS=10327;
SAO=0;SCS=0;SSR=0;VC=SNP;VP=050000000005000000000100;WGT=1;dbSNPBuildID=132
chr1       10433   rs56289060      A       AC      .       PASS    ASP;RSPOS=10433;
SAO=0;SCS=0;SSR=0;VC=INDEL;VP=050000000005000000000200;WGT=1;dbSNPBuildID=129

Any ideas?

sed 's/^1/chr1/' input_file

Thank you Shell, but I forgot to mention that some of my other lines begin with numbers like such:

1 10440 rs112155239 C A . PASS ASP;OTH;RSPOS=10
440;SAO=0;SCS=0;SSR=0;VC=SNP;VP=050000000015000000000100;WGT=1;dbSNPBuildID=132

Is there a wildcard to represent white space for sed?

sed 's/^1[^0-9]/chr&/1' infile

Problem resolved