tools to simulate slow network bandwidth

try Traffic Shaper XP you can easily limit speed of IE or other browser with this App and its also freeware
Traffic Shaper XPhttp://bandwidthcontroller.com/trafficShaperXp.html
If you do not mind configuring a Linux box I have found NIST Net (http://snad.ncsl.nist.gov/itg/nistnet/) to be a great free solution to my network emulation requirements.
My work uses this tool, and it seems quite good: http://www.dallaway.com/sloppy/
Best of luck.
TMnetSim Network Simulator version 2.4 32-bit (600KB)PC Platform software to simulate a bad WAN on a PC. Newer version than in ToolCrib, also does Packet Capture.http://www.tmurgent.com/download/TMnetsim32_02040000.zip
http://www.linuxfoundation.org/en/Net:NetemOn Linux, see netem: the kernel already contains support for traffic shaping, and can simulate high latency, low bandwidth, packet losses, and all sort of other adverse conditions, even on a loopback device (so you don't need a real, physical network to test across).

the OSI model wiki

(wiki)
The OSI Model

7. Application Layer
NNTP · SIP · SSI · DNS · FTP · Gopher ·
HTTP · NFS · NTP · SMPP · SMTP ·
SNMP · Telnet (more)

6. Presentation Layer
MIME · XDR · SSL · TLS

5. Session Layer
Named Pipes · NetBIOS · SAP

4. Transport Layer
TCP · UDP · PPTP · L2TP · SCTP

3. Network Layer
IP · ICMP · IPsec · IGMP

2. Data Link Layer
ARP · CSLIP · SLIP · Frame Relay
· ITU-T G.hn DLL

1. Physical Layer
RS-232 · V.35 · V.34 · I.430 · I.431 ·
T1 · E1 · 802.3 Ethernet
· 10BASE-T · 100BASE-TX
· POTS · SONET · DSL
· 802.11a/b/g/n PHY · ITU-T G.hn PHY