To just check the size of your download type
ls -l fsl-4.1*
and compare it with the relevant file below

> ls -l fsl-4.1*
-rw-r--r-- 1 cowboy analysis 1361091684 Jan 14 13:16 fsl-4.1.7-centos4_32.tar.gz
-rw-r--r-- 1 cowboy analysis 1412198398 Jan 14 14:16 fsl-4.1.7-centos4_64.tar.gz
-rw-r--r-- 1 cowboy analysis 1370911031 Jan 14 14:03 fsl-4.1.7-centos5_32.tar.gz
-rw-r--r-- 1 cowboy analysis 1425582726 Jan 14 13:37 fsl-4.1.7-centos5_64.tar.gz
-rw-r--r-- 1 cowboy analysis  283355768 Jan 19 10:41 fsl-4.1.7-feeds.tar.gz
-rw-r--r-- 1 cowboy analysis 1632647770 Jan 14 14:46 fsl-4.1.7-macosx.tar.gz
-rw-r--r-- 1 cowboy analysis 1240050898 Jan 18 09:59 fsl-4.1.7-sources.tar.gz
-rw-r--r-- 1 cowboy analysis 1361156642 May 15 14:04 fsl-4.1.8-centos4_32.tar.gz
-rw-r--r-- 1 cowboy analysis 1412274859 May 15 14:52 fsl-4.1.8-centos4_64.tar.gz
-rw-r--r-- 1 cowboy analysis 1371032726 May 15 14:34 fsl-4.1.8-centos5_32.tar.gz
-rw-r--r-- 1 cowboy analysis 1425623550 May 15 14:18 fsl-4.1.8-centos5_64.tar.gz
-rw-r--r-- 1 cowboy analysis 1632465751 May 15 15:10 fsl-4.1.8-macosx.tar.gz
-rw-r--r-- 1 cowboy analysis 1240127144 May 15 15:33 fsl-4.1.8-sources.tar.gz

To fully check that your file downloaded correctly either run
md5 fsl-4.1*
 or
md5sum -b fsl-4.1*
depending on which program your computer has, and compare it with the relevant value below

> md5sum -b fsl-4.1.7-centos4_32.tar.gz
f3612e2bcf552390f72ee6871fe347af *fsl-4.1.7-centos4_32.tar.gz

> md5sum -b fsl-4.1.7-centos4_64.tar.gz
ea699a3ec9d6370c8f9cecf7f411360a *fsl-4.1.7-centos4_64.tar.gz

> md5sum -b fsl-4.1.7-centos5_32.tar.gz
d8486a2899361821f9042d02875ed56f *fsl-4.1.7-centos5_32.tar.gz

> md5sum -b fsl-4.1.7-centos5_64.tar.gz
59ebc08fe2e2a12812704ea1ff963f61 *fsl-4.1.7-centos5_64.tar.gz

> md5sum -b fsl-4.1.7-feeds.tar.gz
b41a77b98751b17ad50dd2a4f424e9f8 *fsl-4.1.7-feeds.tar.gz

> md5sum -b fsl-4.1.7-macosx.tar.gz
267f1a41ea57f6cb58528f519a4ab83d *fsl-4.1.7-macosx.tar.gz

> md5sum -b fsl-4.1.7-sources.tar.gz
ecc01ab6ca3070397823a4dd0dd54630 *fsl-4.1.7-sources.tar.gz

> md5sum -b fsl-4.1.8-centos4_32.tar.gz
e9f3b6edb9542c5c11786c0737465c1f *fsl-4.1.8-centos4_32.tar.gz

> md5sum -b fsl-4.1.8-centos4_64.tar.gz
86bd58ff6ff73dd2594c3238af037006 *fsl-4.1.8-centos4_64.tar.gz

> md5sum -b fsl-4.1.8-centos5_32.tar.gz
bbd48e4b847055f2e84831a2ae869450 *fsl-4.1.8-centos5_32.tar.gz

> md5sum -b fsl-4.1.8-centos5_64.tar.gz
92679e230a27e30266a01a6953fbff4a *fsl-4.1.8-centos5_64.tar.gz

> md5sum -b fsl-4.1.8-macosx.tar.gz
da9c72bb431979df1fdd17310136cd11 *fsl-4.1.8-macosx.tar.gz

> md5sum -b fsl-4.1.8-sources.tar.gz
6887dd360340e3d665be81c6cffbbe5c *fsl-4.1.8-sources.tar.gz