According to you, the drives you select open in a new window. Try to change the browse settings of your folders. Open My Computer, on that window go to the Tools Tab, choose Folder Options, and then on the General tab you should see the Browse folder options. There you are given choices, whether to open the folders using its own window or in the same window. Choose the option that allows you to open in the same window, and then click on Apply then OK.
For the slow performance of your computer, you may do a disk clean up then after that you can defrag your drives. To do this, go to the Star button, choose Programs, then Accessories, System Tools and Disk Cleanup. Choose the drive you want to clear out. This then allows you to select the folders that you would like to be emptied. After Cleaning-up the folders you should defrag the drive you recently removed files from. Do this in order to rearrange the files saved on your disks. This rearrangement of files enables a faster computer start-up, a larger disk space and speedier program response. Note that, defragmentation does not physically change your file locations; it only provides additional spaces for your files. The Disk Defragmenter is also found in the System Tools. An often defragmentation is suggested for computers with frequent internet usage and enormous file quantity.